Various studies indicate that risky behavior has a substantial genetic component. For instance, a substantial part of the variation in the initiation of substance use can be explained by genetic factors: alcohol (37%), 9 nicotine (44%), 10 and cannabis (40%–48%). 11 Even higher heritability estimates are shown for substance use disorders, for example, alcohol: 45%–73%, 9 , 12 nicotine: 44%–75%, 9 , 10 , 12 and cannabis: 37%–59%. 11 , 12 Furthermore, the heritability of risky sexual behavior was estimated by previous research to be around 33%. 13 It is assumed that different risky behaviors might merely reflect different phenotypic manifestations of (partly) shared underlying genetic vulnerabilities. 14 , 15 However, it is largely unknown which genetic and biological mechanisms underpin the heritability of risky behaviors. 16
