Abstract
The current study examined the extent to which gender/sex preference moderated the role of cohabitation on incest avoidance in an online sample of 1,623 adults with at least one opposite-sex sibling. Consistent with previous research, we found that longer cohabitation with a sibling was associated with decreased sexual interest in sexual contact between hypothetical siblings. We extended the literature by finding that gender/sex preferences contribute significantly to our understanding of incest avoidance. Among female participants, we found that higher attraction to males was correlated with greater disgust toward hypothetical sibling incest, diminished sexual interest in hypothetical sibling incest, and fewer reports of sexual contact with their siblings. Among male participants, gender/sex preferences significantly moderated the relationship between cohabitation and reported sibling sexual contact. Males with higher attraction to females who had shorter cohabitation reported more sibling sexual contact compared to those with longer cohabitation; in contrast, males with higher attraction to males reported similar levels of sexual contact with siblings regardless of cohabitation length. Our findings emphasize the importance of considering gender/sex preferences to better understand the mechanisms underlying sibling incest.