Parental skills, assortative mating, and the incidence of autism spectrum disorder

We assess theories that autism spectrum disorder (ASD) is heritable and transmitted through parental skills using data from Denmark. We construct parental skill measures by mapping Danish occupations to the Occupational Information Network (O*NET) survey of US occupations and principal factor analysis. We find that fathers’ skills are linked to ASD in children. A one standard deviation increase in a systems and ordering skills factor correlates with a modest but statistically significant 0.041 percentage point (2.4 percent) increase in ASD incidence. There is a negative and slightly larger relationship with communication skills. ASD also is similarly correlated with Deming’s (2017) routineness and social skills measures, and fathers again play larger roles. We also find evidence consistent with Baron-Cohen (2002) whereby extreme personality traits in parents affect ASD incidence; having two parents with high systems and ordering relative to communication skills leads to a 35 percent higher diagnosis rate than having parents with “balanced” skills. While all of these estimates are meaningful given the costs of ASD, they explain only a small fraction of variation in ASD diagnoses. Finally, although assortative mating on skills exists, we cannot detect a role for it in recent dramatic increases in ASD.