Parental genes can influence their children, even if the genes are not passed down at all, according to a new study. Instead, the parents' nature – or genetic makeup – impacts how they nurture their children, a phenomenon called 'genetic nurture'.
'The discussion of nature versus nurture is often framed so that the two factors are treated as, if not competitive, independent forces. This study illustrates that not only do genes and nurture often work hand in hand, there is a genetic basis to nurture,' said lead author Professor Augustine Kong of the University of Oxford.
Each parent passes down one copy of their genes to their children. The researchers compared genes of 21,637 Icelanders and their parents, and also looked at their educational levels. They found that even gene variants that were not passed down had an effect on how long the children stayed in school. This influence was 30 percent as strong as the genes that were inherited from the parents.
'Variants that have to do with planning with the future could have the biggest effect on nurturing,' Professor Kong told The New York Times.
Professor Philip Koellinger from VU University Amsterdam and Dr Paige Harden from the University of Texas wrote in a comment article in Science: 'This genetic nurture effect is an indirect link between parental genotype and children's characteristics, not caused by the children's own biology but rather by the family environment that covaries with parental genes.'
Dr Piter Bijma, who studies animal breeding and genetics at the Wageningen University in the Netherlands, was not surprised by these results. He told The New York Times: 'Humans provide substantial care to their offspring, and so the nurture they create is very likely to have a genetic component.'
The study focused on individuals and their parents, the parents are also impacted by their parents, and so on. However it is thought that siblings can have a similar effect on each other too. Additionally, not all parental genes have an effect through genetic nurture. The researchers did not find any evidence of genetic nurture in children's height and body weight.
Among wealthy societies, genetic nurture 'might be more relevant for behavior and social achievements than for more biologically proximal outcomes such as body size,' noted Professor Koellinger and Dr Harden. They also mention that taking genetic nurture into consideration could have important implications for social inequality and health, in future research.
Dr Kári Stefánsson of deCODE genetics and author of the study thinks the research could also help understand how the brain works. 'The propensity to nurture is a defining trait for a person that is inseparable from the brain,' he said. 'Identifying sequence variants that contribute to nurture can thus be an important step towards the understanding of the workings of the human brain and what makes humans human.'
The study was published in the journal Science.