The Attention‐Deficit/Hyperactivity Disorder‐Associated DRD4 7R Allele Predicts Household Economic Status but Not Nutritional Status in Northern Kenyan Rendille Children

Around 11% of U.S. children are diagnosed with attention-deficit/hyperactivity disorder (ADHD). One hypothesis for ADHD's relatively high prevalence is that behaviors associated with ADHD were advantageous in past environments where they were positively selected for. A previous study showed that an allele associated with ADHD-the 7R allele of the gene encoding the D(4) dopamine receptor (DRD4)-had a positive effect on the nutritional status of nomadic adult Ariaal men and a negative effect on settled adult men. We attempted to replicate this finding by analyzing the impact of DRD4 7R on children's nutrition and other household metrics in the Rendille, a population closely related to the Ariaal. We genotyped 259 Rendille children aged 5-10 years for DRD4 7R and analyzed this against previously collected anthropometric and household data from two Rendille towns. Analyses were pre-registered (https://osf.io/p8yv2/) before the addition of the 7R genotype to the dataset. DRD4 7R was not associated with iron nutrition, indicated by transferrin receptor (TfR) concentration, height-for-age (HAZ) or weight-for-height Z-scores (WHZ), or with maternal education status. However, DRD4 7R was positively associated with household economic status (p = 0.047). The failure to replicate an association between DRD4 7R and nutritional status might be due to this sample being of children who are not yet substantially provisioning themselves. Given that children's genotypes are correlated with parents' genotypes, it is likely that the effects of the parents' genotypes, rather than the participating children's, explain the association between children's DRD4 7R genotype and household economic success.