Mapping the genetic and environmental aetiology of autistic traits in Sweden and the United Kingdom
AbstractBackgroundAutistic traits are influenced by both genetic and environmental factors, and are known to vary geographically in prevalence. But to what extent does their aetiology also vary from place to place?MethodsWe applied a novel spatial approach to data on autistic traits from two large twin studies, the Child and Adolescent Twin Study in Sweden (CATSS; N=16,677, including 8,307 twin pairs) and the Twins Early Development Study in the UK (TEDS; N=11,594, including 5,796 twin pairs), to explore how the influence of nature and nurture on autistic traits varies from place to place.ResultsWe present maps of gene- and environment- by geography interactions in Sweden and the United Kingdom (UK). Our results suggest that there is higher heritability and lower non-shared environmental influences on autistic traits in more densely populated areas. For example, we observe greater heritability in the more populated and urban areas in southern Sweden and near the main cities in the UK. Non-shared environmental influences are less consistent across the two countries and although these influences tend to be higher in more rural areas, there are also areas of greater influence around cities.ConclusionsWe hope this systematic approach to aetiological interactions will inspire research to identify previously unknown environmental influences on the aetiology of autistic traits. By doing so, we can gain greater understanding of how these environments draw out or mask genetic predisposition and other environmental influences and could lead to health and social policy innovations to support those with ASD and autistic traits.