Being pregnant for the first time at a young age is associated with disinhibitory behaviours, such as low self-control, antisocial behaviour and substance misuse.1-3 A recent genome wide association study (GWAS) demonstrated that genes have a role in these associations.4 Now, researchers have tested the hypothesis that molecular-genetic influences on age-at-first-birth can predict disinhibition.
Leah Richmond-Rakerd and colleagues included nearly 3,000 participants with genotype data from the longitudinal Environmental Risk (E-Risk)5 and Dunedin6 studies in their analysis. They calculated the polygenic risk score for age-at-first-birth and tested whether it was associated with disinhibitory outcomes across the participants’ lives. In both cohorts, the polygenic risk score modestly predicted low childhood self‐control, externalizing psychopathology, criminal offending, substance dependence, and the number of sexual partners. Childhood disinhibition partly mediated the associations between the polygenic score and reproductive behaviours.
“Our findings suggest that age-at-first-birth is a useful measure, not just for researchers who are interested in the genetics of reproductive behaviour, but also for researchers who are interested in the genetics of disinhibition”, explains Richmond-Rakerd. “Going forward, an important goal for future work is to identify the mechanisms that connect molecular–genetic discoveries for age-at-first-birth with disinhibitory behaviours”.
The main author, Leah Richmond‐Rakerd summarises her research in this video abstract
Richmond-Rakerd, L.S., Moffitt, T.E., Arseneault, L., Belsky, D.W., Connor, J., Corcoran, D.L., Harrington, H., Houts, R.M., Poulton, R., Prinz, J.A., Ramrakha, S., Sugden, K., Wertz, J., Williams, B.S. & Caspi, A. (2020), A polygenic score for age‐at‐ﬁrst‐birth predicts disinhibition. J. Child Psychol. Psychiatr. doi: 10.111/jcpp.13224.
1Klein, J.D. et al. (2005). Adolescent pregnancy: Current trends and issues. Paediatrics. 116:281–286. doi: 10.1542/peds.2005-0999.
2Coyne, C.A. et al. (2012). Some (but not much) progress toward understanding teenage childbearing: a review of research from the past decade. Adv. Child Dev. Behav. 42:113–152. doi: 10.1016/b978-0-12-394388-0.00004-6.
3Moffitt, T.E. et al. (2011). A gradient of childhood self‐control predicts health, wealth, and public safety. Proc. Natl. Acad. Sci. USA. 108:2693–2698. doi: 10.1073/pnas.1010076108.
4Barban, N. et al (2016). Genome‐wide analysis identiﬁes 12 loci inﬂuencing human reproductive behaviour. Nat. Genet. 49:1462–1475. doi: 10.1038/ng.3698
5Moffitt, T.E. et al. (2002). Teen‐aged mothers in contemporary Britain. J. Child Psychol. Psychiatr. 43: 727–742. doi: 10.1111/1469-7610.00082.
6Poulton, R. et al. (2015), The Dunedin Multidisciplinary Health and Development Study: Overview of the ﬁrst 40 years, with an eye to the future. Social Psychiatry & Psychiatric Epidemiology, 50:679–693.
Disinhibition: the inability to suppress inappropriate or unwanted behaviours. Affected individuals might show a lack of restraint or regard for social norms, or participate in unnecessarily risky or dangerous activities.
Polygenic risk score: a quantification of the cumulative effects of a number of genetic variants (which might individually have very small effects on susceptibility) on a particular trait with a genetic component.