It has been known for some time that men with older brothers are more likely to be homo- sexual than men without older brothers. One explanation for this effect has been that this is a phenomenon of socialization related to the environment in which males are raised. Bogaert (2006) investigated this possibility by studying 944 people and looking at the num- ber of older brothers and sisters an individual had and whether those were biological sib- lings or step-siblings. With older biological brothers the probability of homosexuality increased from 3% to around 5%, but there was no similar increase with older stepbrothers or with biological sisters or stepsisters. How should Bogaert analyze these data?