Child behaviour problems show biggest gap between DNA-based and twin heritability

DNA-based heritability estimates for behaviour problems in children are surprisingly low, according to a new King’s College London study which examined how far differences between children can be explained by differences in their DNA.

Drawing on genetic data from the Twins Early Development Study (TEDS), the researchers looked at 37 measures of childhood behaviour problems, as assessed by parents, teachers, and children themselves at ages 12 and 16.

Problems in childhood, such as anxiety, depression, hyperactivity, and conduct disorder are common. In the US the likelihood of having one or more such problems is greater than one in 10.

This new study, published in Translational Psychiatry, found that DNA-based heritability contributed very little (6 per cent) to differences between children, even though overall twin heritability was substantial (52 per cent).

For decades, twin studies have consistently shown that childhood behaviour problems are under significant genetic influence, with heritability estimates ranging from around 40 per cent for anxiety and depression to more than 60 per cent for autistic like traits and hyperactivity. Twin studies compare identical twins, who share 100 per cent of their genes, with non-identical twins, who share on average 50 per cent.

DNA-based heritability gives the proportion of variance in each trait that can be explained by common DNA markers, without identifying which DNA markers are associated with the trait. This is different from twin heritability, which is the proportion of variance explained by any inherited genetic variants.

Rosa Cheesman from King’s College London’s Institute of Psychiatry, Psychology & Neuroscience (IoPPN), said: ‘Importantly, we expect DNA-based heritability to be less than twin heritability for all complex traits. This is because it only looks at the effects of the common measured DNA markers detectable by current technology, rather than the effects of any DNA differences between people. What was surprising is that for childhood behaviour problems, DNA-based heritability is so much less than twin heritability, about 5 per cent versus 50 per cent.

‘Our findings have important implications for future genetic studies in this area. We’ll need much larger sample sizes to have a better chance of detecting influential DNA differences between people. We are also trying to think more carefully about how we measure these traits’.

Notes to editors

Paper reference: Cheesman, R et al (2017) Childhood behaviour problems show the greatest gap between DNA-based and twin heritability Translational Psychiatry

For further media information please contact Jack Stonebridge, Senior Press Officer, Institute of Psychiatry, Psychology & Neuroscience, King’s College London on jack.stonebridge@kcl.ac.uk or 020 7848 5377.