Having more testosterone makes men more aggressive – right? It’s a popular lay belief that’s supported by animal studies, but there’s been very little relevant research in humans. Now a study, published in Psychological Science, reveals a more nuanced picture: some men are more affected by raised levels of testosterone than others.
In our culture we like to speculate about the effects of different parenting styles on children. A lot of this debate is wasted breath. Twin studies – that compare similarities in outcomes between genetically identical and non-identical twins raised by their biological or adopted parents – have already shown us that parental influence is far more modest than we usually assume. Now a paper in Social Psychological and Personality Science goes further, using the twin approach to reveal how it is mistaken to see the parent-child dynamic as a one-way relationship. “Given the current evidence … it is more accurate to conceptualise parenting as a transactional process in which both parents and children exert simultaneous and continuous influence on each other,” write Mona Ayoub at the University of Illinois at Urbana-Champaign and her colleagues.
It’s timely, then, that a team of researchers, led by psychologist Emily Willoughby at the University of Minnesota Twin Cities, recently surveyed over 1000 online US participants, asking them about their personal circumstances, education, political orientation, and also to estimate the relative contribution of genes and the environment to variation in 21 different human traits, from eye colour to intelligence. This is probably the most detailed study to date of people’s insights into behavioural genetics, and the findings have just been published as a pre-print at the Open Science Framework.
Around the world, neuroscience evidence is being introduced into courtrooms at an increasing rate, including findings from behavioural genetics. Specifically, some legal teams for the defence have been allowed to argue that the defendant has a low activity version of the MAOA gene, which codes for an enzyme that regulates the levels of several neurotransmitters. In combination with experiencing child abuse or maltreatment, having this low activity gene has been linked with increased impulsivity, including aggression. Defense lawyers presumably hope that jurors will interpret this as meaning the defendant was less culpable for their violent crime. However, before now, little research has examined how jurors will treat this evidence.
For a new study in Behavioral Sciences and the Law, Natalie Gordon and Edie Greene presented 600 mock jurors (half were students, half were from the wider community) with a detailed trial summary based on a real US murder trial in which the defendant, already in jail for an earlier crime, had murdered his cell-mate. The jurors’ task was to decide whether he should face the death penalty.
Exactly how parents shape their children is a matter of controversy, especially since Judith Rich Harris’ book The Nurture Assumption popularised the behavioural genetics position that the “shared environment” (so-called because it’s shared by siblings) – including the family home and parents’ methods of upbringing – has scant influence on how children turn out. But the debate is far from settled, and now a team chiefly from Florida State University has investigated whether more educated parents produce offspring with particular personality characteristics. Published in the Journal of Personality and Social Psychology, the research identifies a number of personality differences that correlate with parental education, and the researchers suggest the causes of this association must be more than just genetics.
Have you seen those people who come out of an exercise class with a spring in their step and self-satisfied smile on their face? They really pushed themselves this time and now they’re riding that endorphin high. To them, the ache and burn feels good. But it’s not so for everyone. Others find exercise unpleasant and unrewarding – the aches just, well, ache. Psychologists call this difference the “affective response to exercise” and in a paper in Psychology of Sport and Exercise researchers in the Netherlands report new evidence that it is to a significant degree genetically inherited.
To understand the drivers of a psychopathic personality (marked by callousness, disinhibition and superficial charm), it’s worth looking at our closest relatives. Some chimps, like some people, score highly on scales designed to evaluate psychopathic tendencies. And new work in Frontiers in Neuroscience reveals a potentially important genetic contributor to psychopathic traitsin chimps, which could lead to a better understanding of the traits in people.
Jeb Bush’s failure to secure a Presidential triple-play is memorable perhaps because it’s an exception to a familiar routine: the family dynasty. It’s a routine especially common in the arts, where a writer’s family tree is apt to contain a couple of actors, a director, and maybe a flower arranger to boot. This might simply reflect upbringing – or maybe the powers of nepotism – but creative success also owes to temperament and talents, some of which may have their origins in our genetic makeup. The journal Behavioural Genetics has recently published a heritability study that explores how deeply a creative vocation sits in our DNA.
We know from twin and family studies that our personality is to a large degree – probably around 40 per cent – inherited. Geneticists are busy trying to find the specific gene variants involved, but because each one on its own only exerts a modest influence, this is challenging research requiring huge samples. A new study in Nature Genetics has made a significant contribution, using the technique of Genome Wide Analysis to look for genetic variants that correlate with personality. The researchers led by Min-Tzu Lo at the University of California, San Diego have identified variations in six genetic loci that correlate with different personality trait scores, five of which were previously unknown. In a separate analysis, the researchers also showed that many of the genetic variants involved in personality overlap with those involved in the risk of developing mental health disorders.
Just over ten years ago, a fascinating journal article argued that some children are like orchids – they don’t just wither in response to a harsh upbringing, they also flourish in a positive environment, unlike their “dandelion” peers who are less affected either way. Since then, research into this concept has exploded. A new meta-analysis in Psychological Bulletin usefully gathers all that we know so far about one key aspect of this – the associations between children’s temperament (the forerunner to adult personality) and the way they respond to different parenting styles. The results suggest that those with a particular kind of highly emotional temperament are more likely to match the description of an orchid child*. Continue reading “Some children are extra sensitive to parenting style, bad and good”→