Hansen SN, et al. - Followed through 2011-2015, researchers performed population-based cohort study of 1998-2007 livebirths from California, Denmark, Finland, Israel, Sweden and Western Australia to determine autism spectrum disorder (ASD) recurrence risk among siblings and cousins. Among 2,551,918 births included to assess recurrence in ASD, 29,998 ASD cases were noted; among 6,110,942 births used to estimate childhood autism (CA) recurrence, 33,769 cases of CA were identified. They noted an 8.4-fold increase in the risk of ASD following an older sibling with ASD and a 17.4-fold increase in the risk of CA following an older sibling with CA when compared to the risk in unaffected families. The risk for cousin recurrence was 2-fold for both disorders. Sex seemed to influence significantly the sibling ASD recurrence risk.