“The Heritability of Autism Spectrum Disorder”, Sven Sandin, Paul Lichtenstein, Ralf Kuja-Halkola, Christina Hultman, Henrik Larsson, Abraham Reichenberg2017 (heritability, autism)⁠:

This study reanalyzes Swedish cohort data to assess the stability under alternative assumptions and models of a previous estimate of the heritability of autism spectrum disorder.

…The study included 37,570 twin pairs, 2,642,064 full sibling pairs, and 432,281 maternal and 445,531 paternal half-sibling pairs. Of these, 14,516 children were diagnosed with ASD. The model including additive and nonadditive genetic, shared and nonshared environmental parameters was chosen as the full model under which nested sub-models were tested. The best-fitting model included only additive genetic and nonshared environmental parameters (Table 1).

Using this model, the ASD heritability was estimated as 0.83 (95% CI, 0.79-0.87) and the nonshared environmental influence was estimated as 0.17 (95% CI, 0.13-0.21). In the full model, the shared environment variance was estimated as 0.04 (95% CI, 0.00-0.14); nonshared environment, 0.16 (95% CI, 0.05-0.30); nonadditive genetic, 0.10 (95% CI, 0.00-0.38); and additive genetic (heritability), 0.69 (95% CI, 0.40-0.86).

Using only twins, the heritability was estimated as 0.87 (95% CI, 0.68-0.96).