Subtitles section Play video Print subtitles >> Good afternoon, everybody. A very warm welcome to today's UCL Lunch Hour lecture. It is my great pleasure to introduce Essi Viding, professor of Developmental Psychopathology in the UCL division of Psychology and Language Sciences. Professor Viding's lecture for us today is entitled, Why do some people become psychopaths? >> Thank you. Individuals with psychopathy tend to capture public imagination. People are fascinated by what makes these individuals so different. And there has been a tendency to at times sensationalize the condition and the description of the condition in the media. And I guess one of the signs that these individuals really do capture the public imagination is that they have featured in a number of popular films. So here we have a picture of Jacob, a character from Buckham [assumed spelling] Films and he's very impulsive and he's also entirely unconcerned about the impact of his behavior on other people and he seems to lack empathy. We have Kevin who is from the movie, We Need to Talk about Kevin. This is a very chilling description of a child who's not capable of forming attachment relationships with his parents who's cruel to animals and cruel to younger children who ends up by the end of the film and the book that it's based on becoming a killer. He kills family members and also people at his school. We have Anton Chigurh who's an absolutely chilling contract killer in the current Coen Brothers film, No Country for Old Men. And if anyone has seen the film, I think one of very scary things about observing this character is when you see shots that are focused directly at his eyes and there really is no emotion coming back to you from those eyes. And then there's probably everyone's favorite psychopath from movies, Hannibal Lecter from the Silence of the Lamb film; and he is again, a very good example of a psychopathic character in that he's entirely void of empathy for other people and he's also extremely skillful at manipulating other people to his own ends. And in fact, if you asked members of the general public what springs to mind when they hear the word psychopath, people often think about serial killers. And real-life serial killers include characters such as Ted Bundy who killed at least 30 women in America in 1970s. He was very bright and extremely handsome, and he often posed as somebody who was in a position of authority or someone who was very reliable to entice these women to come with him, and then he murdered them in a very cruel way. And people think that he actually may have committed many more crimes than he confessed to. His description of himself was that he's the most cold-hearted son of a bitch you'll ever likely to meet. And interestingly his defense lawyer didn't have a lot of good things to say about him either and said that he was the very definition of heartless evil. So this was a man who was able to be very charming, was able to convince other people to come with him, but he actually turned out to be somebody who felt absolutely nothing for his victims and didn't seem to really feel any guilt for what he had done. But, of course, not all psychopaths are serial killers. In fact, only a very few are. So what are the characteristics that define an individual with psychopathy? Well, one of the most prominent characteristics is their lack of remorse and guilt. So they simply do not feel bad about the things they have done. They may sometimes say that they do if they perceive that as getting them something that they want such as early release from prison. But it's very clear from the way they behave and -- that they do not actually experience remorse for what they have done. They don't feel bad about what they have done. They're very shallow affect. Their emotions appear ingenuine and often very short lived. They don't form typical attachment relationships. They don't look after the people around them. They can often have superficial charm. So if you meet these individuals for the first time, you may be very, very alert by them. They may seem very gregarious, very charming, very nice. But once you get to know them for a longer period of time that charm tends to wear off. They often have a grandiose sense of self worth. They think they are better and more deserving than other people. They're pathological liars and they are typically very good at manipulating other people to their own ends. As a developmental psychologist I'm very interested in how these characteristics develop. It's unlikely that anybody's born a psychopath but clearly you don't get this sort of conditions as a birthday present when you turn 18 either. So the research in our group has been focused on investigating what makes some children developmentally vulnerable to developing these sorts of personality traits as an adult. And you can focus on various different levels of query when you try and understand the development of this condition. So we can look at how children who are at risk of becoming adult psychopaths look like behaviorally. What differentiates these children from typical developing children or other children who may have behavioral problems but who don't exhibit these cold characteristics of lack of empathy and guilt. We can study how these children see the world around them so we can use experimental tasks to focus on their psychological level analysis. And we can see if these children's brains react differently to information around them which is what you would expect if their behavior and if their way of processing information is different. And you can also use genetically informative designs to study the relevant importance of genetic and environmental factors in developing this type of condition. And you can also try and look for specific risk genes and risk environmental factors that in concert might promote the development of the disorder. Now we'll first tell you a little bit about what makes these children behaviorally different from their typically developing peers but also from other children who have behavioral problems. So there are several early behavioral warning signs of children who are at risk for psychopathy and these look very different from the kinds of characteristics we see in adult psychopaths. The person who first formally downward extended this psychopathic criteria to children was Paul Frick and this was work that started 20 years ago in the United States and now several different research groups across the globe have studied these behavioral characteristics in children and in young people. These children lack remorse and guilt so they don't express that they're sorry for what they've done. They lack empathy and this can be often manifested by them behaving cruelly amongst other children, bullying, being very physically aggressive in a way that is really showing no concern over developing of the other person. They are also sometimes cruel to animals such as pets in the family. They have shallow affects so many of the parents report that they don't feel like they can connect with this child. They may have a perfectly nice relationship with their other children and if anyone has read the book, We Need to Talk About Kevin, I think that's a very good example of a mother who was able to form an attachment relationship with one of her children, but really felt like there was nothing coming back from the child who went on to develop psychopathy. These children can manipulate other people for their own gain. And they have a sense of being more important and more deserving than other people. And in combination this constellation of traits in children is called callous-unemotional traits. So clearly we don't want to label children as psychopaths but this constellation of traits gives you a warning sign that the child who scores very high on these traits may be at risk for developing psychopathy in the adulthood. They're kind of like the warning sign. You want to start thinking about doing something to help this child if they display this constellation of characteristics. There's now quite a bit of good longitudinal research showing that these sorts of traits are predictive of persistent, violent and severe antisocial behavior and psychopathy in adolescents and adulthood. They don't predict that every child who's score high on these sorts of traits will inevitably become an antisocial adult but they do index that that child is at a significantly increased risk of developing the antisocial presentation in adulthood. Antisocial behavior in children is called conduct problems. And if you think about this circle that I'm showing to you as representing all the children with conduct problems and the blue circles as representing the minority who also has high levels of callous-unemotional traits and you get an idea that they are a minority but they are a sizable minority. So people estimate that somewhere between 25 to as high as 50 percent of the children who are diagnosed with conduct problems also have this presentation of high callous-unemotional traits. And what sets them apart from other children with conduct problems is that they often engage in proactive or planned acts of aggression. So while the aggression in other children with conduct problems is typically quite impulsive and in reaction to something external that happened, for instance, a perceived threat or slight to the child, these children can engage in aggression if they think it's going to get them something they want. It might get them status among peers. It might get them some goods that they desire. As I've already said they lack guilt. They don't worry about hurting other people to get what they want and they often have low levels of anxiety. And this is in contrast with the remainder of children with conduct problems who have low levels of callous-unemotional traits and who often aggress when they feel under threat and whose aggression is often impulsive. It's not premeditated. And when these children have had a chance to reflect on what they have done, they actually often feel bad and guilty about having hurt other people or having done something that has caused their parents or their teachers to feel sad. And this presentation can also occur with high levels of anxiety. So you already are beginning to see from this behavioral data that the reactivity, emotional reactivity profile of these two types of children with conduct problems is quite different. You have a group that seems to be more cold and calculated and unemphatic, and then you have another group who seems to be more hot headed, reactive, and impulsive but who also has the capacity to empathize with other people. So these different behavioral profiles have got psychologists interested in how these children may see the world around them differently from typically developing children but also their peers with conduct problems. And we can focus on the study of the psychological level of analysis by giving children experimental tasks which we often present on a computer, for instance, and these tasks can give us an idea of how they process information such as facial, emotional expressions. So I want you to have a go at doing one of the tasks that we do with the children. Here's a face that is starting with a neutral rather calm expression and I'm going to press a button and it's going to start slowly developing an emotional expression. And when you think you know what the expression is, please shout it out loud and don't be shy. Okay. Happy. Very good. So you can see fairly early on in the development of this expression that this is somebody who's looking happy, their corners of the mouth are going up which you can see a display of teeth. This is a happy looking chap. And here's the same chap putting a different expression. And again shout out when you think you know what emotion this person is displaying. Scared. So I'm hearing people say scared so this is somebody who is fearful. And you can see that this person is scared because they are showing a lot of eye white. This is one of the very, very ecologically valid signs that somebody's scared when their eyes are looking a little bit large and you can see a lot of the eye whites. Now children who have conduct problems and high levels of callous-unemotional traits have difficulty in recognizing and reacting to other people's emotions particularly emotions of distrust, such as fear and also sadness which is -- you see here at the top right-hand side -- sorry. Bottom right-hand side. And people have used facial stimulus -- that's what I just showed to you to assess this. But people have also used stimuli that is auditory so people doing vocalizations that emotional or body postures. And this work by our lab and labs of our colleagues have very conclusively shown that these children really do not appear to process other people's emotions in a typical fashion. They seem to be underreactive to these displays of emotions and unable to recognize them as effectively as typically developing children do. Interestingly they also report feeling less fear themselves. And one of the things that we're interested in researching in our lab at the moment is whether the reason they have such difficulty in processing other people's emotions stems from the fact that they don't feel those same emotions very strongly themselves. So it's probably tricky to empathize with other people and to recognize their emotions if you have an impoverished experience of those same emotions yourself. We also know from standard learning paradigms that these individuals who have conduct problems and high callous-unemotional traits are less responsive to punishment. So when you have to learn about which stimuli is good to go for and gives you points and which stimuli is bad to go for and doesn't give you points, these individuals are typically poorer at modulating their behavior in response to the punishment used. And people have theorized that one of the reasons why these children may be tricky to socialize is that two very powerful tools of socializations are not as effective for them. So anyone who has small children in the audience or has dealt with small children knows that when they misbehave, we often give them sanctions. So in my house at the moment with the three-year-old we have a naughty step and he sits there relatively regularly and so it's something that I employ in my house. It's very effective. He doesn't like sitting on the naughty step. He said he'll kind of improve his behavior and he usually comes and joins us and he indeed does improve his behavior because he doesn't like being excluded from the activities. And we also do empathy induction. So anyone who's dealt with toddlers has basically repeated, well, think how Johnny is going to feel if you whack him with the toy car until they're blue in the face. So we try and get the children to focus on how their behavior might impact somebody else and somebody else's emotions. Now if you are really incapable of feeling perhaps those emotions yourself and also feeling for other people, and if you don't react very much to the punishments, there are two very powerful socialization tools that are not going to be as effective in bringing you up as they are in typically developing children. So really what we see in these children is this diminished emotional responsivity to both, kind of, more material punishments but also in terms of their reactivity to other people. And this profile is in contrast with the profile we see for children who have conduct problems but who have low levels of callous-unemotional traits. These children, if anything, seemed to be a bit emotionally overreactive. They have what psychologists call a hostile attribution bias. So they tend to see threat in even stimuli that typical individuals don't perceive threatening. So they might see an ambiguous face and think that this is somebody who's trying to get at me so I'm going to aggress first. So in this group what we see really is increased emotional reactivity at least to some types of stimuli. And these data have got ourselves and also other groups interested in looking at how these children's brains look like when we show them emotionally charged stimuli. One of the ways in which we can study how the brain processes information is by scanning children using functional magnetic resonance imaging. This is a noninvasive technique that involves scanning for children's brains as they lie inside the magnet. And they do tasks that we have sent to them. We can then look at their brain activity as they are doing the tasks and this gives us an idea of what parts of the brain are engaged in processing the information that we show them. One of the brain areas that researchers on conduct disorder have or conduct problems have focused on is called the amygdala. And this is a very small almond shape part of the brain. It's a very preserved structure even reptiles have it. It's there for basically alerting you that there's something salient in the environment that you're to pay attention to. And this salient information for human beings includes emotions of other people. And studies of children with conduct problems using emotional stimuli have been a little bit mixed. Some studies have reported increased amygdorial [assumed spelling] reactivity to emotional stimuli. Other studies have reported decreased amygdorial reactivity to emotional stimuli. And our group recently wanted to investigate whether it's the callous-unemotional traits that determine whether the children's brains are underresponsive or the amygdors are underresponsive to emotional stimuli or overresponsive to the same stimuli. So we have carried out a range of paradigms recently. I will talk about two here in the talk. And here's an example of a recent task that we've used called masked fear task. And in this task we presented either fearful faces which is on the left-hand side there or calm faces which is on the right-hand side there for very short duration, only 17 milliseconds. And then we replaced those faces with a calm face of a different identity. And the replacement of the face happened so quickly that the participants are not consciously aware that they've seen a fearful face. So the advantage of this task is that we can look at very early preconscious processing of emotion. In other words, we get an idea of how automatically the brain attunes to the emotional stimuli. And when we contrast the fear and the calm conditions we find a pattern of brain responses where children who have conduct problems and high callous-unemotional traits show very low amygdorial reactivity to these preconsciously presented fierce stimuli. The typical children are somewhere in the middle and the children with conduct problems and low callous-unemotional traits show, if anything, overreactivity to these fear faces that we present pre-attentively. And here I'm showing you a plot of the data from the children with conduct problems alone. And on the left-hand side on the Y axis you can see the brain activity estimates from the FMRI analysis and on the right-hand side you can see the child's callous-unemotional traits score. And you can see that the higher the callous-unemotional trait score, the lower the amygdorial response to these fearful faces. We also used a more complex emotional tasks such as the task that showed scenarios of other people in distress. So this was a cartoon task where the children saw a scenario where the mother is reading a newspaper, a child is going down the slide, and the child ends up hurting himself and falling off the slide. And then the person inside the scanner gets two choices as to what is the appropriate ending to the task. And most children even the children with conduct problems are very able to say that the appropriate response is for the adult to go and comfort the child. So behaviorally the children -- process this task very similarly. But interestingly again, the amygdala of the children with conduct problems particularly those children with conduct problems and callous-unemotional traits is less reactive to observing other people in distress in this very complex social scenario. And the kind of contrast we can use in a scanner is we have a similar scenarios but without the emotional contents so we can really extract the emotional response of the brain. So the data from this behavioral psychological and brain emitting studies is really showing this picture of shallow affect and lack of empathy and demonstrating it in different levels of analyses. So we know from naturalistic behavioral settings from more experimental behavioral settings and also from brain imaging settings that these children really seem to have this underreactivity to other people's emotions, perhaps particularly distress. So these sort of data obviously begs the question as to why do these children process the information around them so differently. Are they genetically at risk for being this way? Are there some environmental risk factors that mean that they come to be very unemphatic, very emotionally underreactive. And one of the ways in which you can wrote the origins or the etiology of any given trait or disorder is by classical twin design. And the twin design relies on a comparison between identical or monozygotic twins and nonidentical or dizygotic twins. The identical twins are the result of a single fertilized egg splitting so they are for all intents and purposes each other's genetic clones. And an example I often use here, I run the research group with Dr. Eamon McCrory who's an identical twin. And his brother has three children but if they did a paternity test, they couldn't tell whether it's the brother or whether it's Eamon who's the father. So these are two individuals who have identical DNA. Then we have nonidentical or dizygotic twins who are the product of two separate eggs being fertilized by two separate sperm. So they're like any other sibling pair but they have been born at the same time which makes them a good comparison in the studies for the identical twins. And you can use the twin studies to infer the relative importance of genetic and environmental influences on variation on any given trait. And the way you can do it is you can compare how similar do these clones look to each other on any given behavior and how similar do these nonidentical twins look to each other on any given behavior. And you can conclude that there is more than likely to be genetic influence on a trait if the identical twins look more similar to each other than the nonidentical twins. So if genetics are important in driving similarity, then the individuals who share hundred percent of their DNA should look more similar to each other than individuals who share on average 50 percent of their DNA. You can also conclude that there may be environmental factors that make family members similar to each other. If the nonidentical twins correlate with each other or resemble each other more than the half of the identical twin resemblance. So if you think that only genetics are important for driving similarity then the dizygotic twin resemblance should be exactly half of the identical twin resemblance. Now if the dizygotic twin resemblance is actually larger than half the identical twin resemblance, this tells us that there are some environmental factors that act over and above genetic factors to promote similarity between family members. And we can also infer that there are some individual specific or nonshared environmental factors if the identical twins are not 100 percent identical in the trait. So these [inaudible] of the genetic clones to the extent that they differ on any given feature, there must have been some environmental influences that differed between the twins. And an example I often use to drive this point home is if you manage an identical twin who grew up in Britain versus an identical twin who went to live in Australia, you would expect that there are chances and differences in pigmentation between these twins because one of them is exposed to constant sun and the other one has to deal with the kind of weather that we've been having last week. So this is environmental factor that differed between the twins and drives differences between family members. And we have used the twin design to ask whether there are differences in the relative importance of genetic and environmental factors for the development of conduct problems in children who have high callous-unemotional traits and in children who have low callous-unemotional traits. And I've been fortunate to work with a very big twin registry that is headed by Robert Floman [assumed spelling] of the Institute of Psychiatry here in London. And what we were able to do because this was a very large twin sample is to select those children who are in the top 10 percent for conduct problems for the twin sample. So they are scoring in an atypical range for conduct problem. And then we divided this extreme group to two. We took those children where either 1 or 2 members of the twin pair also scored in the top 10 percent for callous-unemotional traits. And then we looked at children where neither member of the twin pair scored in the top range for callous-unemotional traits. And within each of these groups we were able to compare the identical and nonidentical twins to give us an indication of how heritable are the conduct problems for children who have callous-unemotional traits and how heritable are conduct problems for children who have low levels of callous-unemotional traits. What we found was that for children who had high callous-unemotional traits the conduct problems were strongly heritable. Whereas for children who had low levels of callous-unemotional traits environmental influences both shared and nonshared were more important for the development of conduct problems. Now that doesn't mean that the children who have high callous-unemotional traits are somehow genetically destined to become antisocial. And but it does mean that they will probably have more vulnerability, innate vulnerability for developing conduct problems. Similarly it doesn't mean that the children who have low levels of callous-unemotional traits have no genetic risk whatsoever but it may be that that takes different form and may require some environmental factors to express or more environmental factors that you may need to express this vulnerability if you have high callous-unemotional traits. Of course the twin studies only give us an idea of the relative importance of genetic and environmental factors and they don't tell us what the actual genes are or the actual environments. And currently there is very scarce data about the actual genes and actual environments particularly for children with high callous-unemotional traits. So ourselves and other people have speculated that the risk genes for high callous-unemotional traits and low callous-unemotional traits type antisocial behavior may be different. And this would be in line with the fact that the other group is associated with low emotional reactivity whereas the other one is associated with high emotional reactivity. So in a way you would expect there to be different vulnerability genes for the two groups. Perhaps genes that confer low emotional reactivity and arousal indicates children with high callous-unemotional traits, and there's certainly some data to support that this may be the case. So a genotype called serotonin transporter polymorphism has been associated with callous-unemotional traits and the allele or the type of that genotype that was associated was the one that confers slower emotional reactivity. We know that from imaging genetic studies. But this is just a single study. Interestingly this genotype only conferred risk in children who lived in low resource neighborhoods. So it suggests that you may have propensity to lack emotional reactivity or lack empathy. But whether that expresses itself as callous-unemotional traits or not may depend on your environmental conditions. There are also some studies that have suggested the genes that may be associated with attachment processes could be important such as the oxytocin receptor gene. But ultimately there haven't really been replications of these findings. We have ourselves conducted a genome line association study which means that we combed through the whole genome looking whether there is anything that crops up and there really weren't any big hits. And there hasn't been [inaudible] case in either our study or any of the other studies. So it's very early days. But if this particular phenotype goes in line with what we know from other behavioral phenotypes and I have no reason to expect that it would be different, we're likely to be spending a long time looks for those genes. They are going to be small genes that probably -- sorry. Genes with small effect size that probabilistically increase the risk for developing this sort of behavioral outcome and it is more than likely that any of this genotypes will require the presence of other risk genes and environmental risk factors in order to penetrate as a risk phenotype. Again, ourselves and others have proposed that for those with no callous-unemotional traits we might be interested in looking for genes that confer high arousal and reactive aggression. And again there's some sensitive data suggesting that these sort of genotypes may be associated with the low callous-unemotional type of antisocial behavior. And genome interaction may be particularly important with regard to this subtype. So there are a number of good studies suggesting that if you have a polymorphism of monoamine oxidase A gene that confers increased unemotional reactivity. And if on top of that you experience maltreatment, then you are at substantial increased risk for developing conduct problems. But very, very early days and all of these studies need more replications and we probably need to really wait for a lot of methodological developments before we can reliably start finding genes associated with this condition. Similarly, the risk environments may differ for the two condition. So we have reasonably good data for the low callous-unemotional trait subgroup. It's reliably associated with hard and inconsistent parenting and maltreatment. But we have less of an idea of what our environmental risk factors that promote development of callous-unemotional traits. And our own work using identical twin differences design where we rely on the fact that they are each other's clones and any differences in phenotype and risk response to environmental factors such as parenting should be where we can reliably say that that's environmental. Using that sort of methodology we haven't been able to show that hard and inconsistent parenting, for instance, predicts increase in callous-unemotional traits. So that doesn't seem to be something that impacts development of those traits or at least not as reliably as it does for the children who have low callous-unemotional traits. And there's some very interesting early data. There's a funny looking carafe with lots of little data points but I will talk you through it. Paul Frick and his colleagues looked at the relationship between hard and inconsistent parenting and conduct problems. And when you look at children who have conduct problems and low callous-unemotional traits, you can see this [inaudible] response relationship. The higher the frequency of hard and inconsistent parenting, the higher the level of conduct problems for these children. But in contrast children who have conduct problems and low levels of callous-unemotional traits appear to have high levels of conduct problems regardless of whether they receive less or more of the hard and inconsistent parenting. Now this is not to say that environmental influences don't matter for these children at all. And in fact there is some very interesting new work showing that for instance parental warmth is associated with lower levels of callous-unemotional traits. So the children may be responsive to some positive environmental influences. There have also been treatment studies that have shown that some parenting focused interventions can be effective in reducing callous-unemotional traits and conduct problems. And there is a Meads [assumed spelling] and -- study showing that if you add empathy training to normal parent training programs, children who have high levels of conduct -- callous-unemotional traits may particularly benefit from this sort of training. At least when it's done with children who are at the preschool, early primary school age range. So some evidence that there are protective environmental factors that can be very helpful for these children. So why do some people become psychopaths? I'm afraid that we have only taken baby steps sofar in terms of research. So we have some inclination but we really don't have a good idea of the development trajectory particularly at different levels of analysis. So there's indication that these children may be more genetically vulnerable but I hasten to add not genetically destined for this sort of outcome. It may be that they lack environmental buffers or they have some risk environmental factors which we don't know what they are that mean that the genetic vulnerability expresses itself as callous-unemotional traits. And we know that they are not very emotionally reactive, empathetic and sensitive to punishment and this sort of presentation at the cognitive emotional level is probably going to make them more resistant to typical socialization efforts. But we also know from longitudinal studies that not all children who have conduct problems and high callous-unemotional traits grow up to be adults with psychopathy. So we really do need more longitudinal studies that combine different methodologies and will enable us to really study what are the environmental risk factors. How may they be different at different time points? How do they influence the development of these children's cognitions and affect processing? So how does the atypical emotion develop over time? And it's interesting to find out that this is something that we are studying at the moment in our group is whether these children can empathize under any circumstances. So if we focus their attention differently or if we use stimuli that they themselves report as sadness or fear inducing, do we then see an emotional response. And if we do can that be harnessed to teach them a bit more about how to empathize with other people. So can we help them to see the world differently? I think that's kind of an important research question for the next 10, 20, 30 years. I know that there are specific interventions being developed that really focus on the difficulties that these children experience and I'm sure that there will be a lot of cross talk between these interventions and the basic science researchers. Some of our basic science findings will feed into how these interventions are tailored more specifically to meet the needs of these children. And of course there is the hope that eventually there will be very few of the individuals who develop psychopathy as an adult outcome. I want to finish by very much acknowledging all the people who are working on our team at the moment and who've worked on our team in the past. This sort of research requires a lot of theoretical knowledge, technical skills, statistical skills, and first and foremost a lot of people skills and when we recruit the samples so when we test the children, we have a very capable team of people who are involved in the research. And I particularly want to acknowledge Eamon McCrory who's there at the Center with me who codirects the research group with me. And also I want to acknowledge the people who are very generously funded our research. And I'm very happy to take questions. Thank you. [ Applause ] And I should also mention that you can go to our lab's website and there will be information about our research and materials in that website. >> Thank you very much. Thank you very much. We have time for one question. >> Sorry. >> Anybody has a good question. It has to be the very best question that can be asked. >> If our high callous-unemotional traits are genetic, that would suggest that maybe one or both of the parents also share some of those traits; so could that be an environmental factor leading to problems? >> So that's an excellent question. So the question was that if these traits are heritable and 1 or 2 of the parents share the traits does that mean that the child is more likely to be exposed to environmental risk. In short, yes. It's a phenomenon that we call gene-environment correlation which is that the parents parent according to that genotype that they pass on to their children so that the child kind of has the double whammy of having genetic vulnerability and then perhaps having a parent who's not really able to provide the optimal parenting environment either. There is some interesting data suggesting that that may not always be the case so there's data from colleague of mine in Australia, Mark Datt [assumed spelling] that has looked at how the children and the parents engage with each other and interestingly at least in the case of the mothers, the mothers of these children try and look for eye contact, try and engage the children just in the same way as any typical mothers do, but the children themselves don't engage in the same way so they don't look the mothers in the eyes. They don't kind of give back in the same way. So while I'm sure that you're right that there are a number of times where the environment is also impoverished because of the parents vulnerability. It's not always the case and sometimes these kind of attachment difficulties may be driven by the child and the very difficult temperament that the child has. >> Thank you very much. Will you join me in thanking Professor Viding again for an excellent lecture? [ Applause ]
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