The heritability (the genetic component of the variance) of addictive disorders has been determined from many thousands of largely European-ancestry twin pairs and ranges from 40% to 60%; the heritability of AUD is around 50%.35 The one published AI/AN heritability study which was in Southwest California Indians produced a heritability estimate of 0.38 for AUD36 and 0.71 for AUD with symptoms of withdrawal.37 Therefore genetic and environmental influences on the development of AUD are both important.
