<p>Same-sex sexual orientation negatively impacts direct reproductive output, but paradoxically, it is persistently expressed across cultures and genetic variation plays a significant role in its development. Existing research has mostly focused on Euro-American cisgender monosexual same-sex attracted males, while comparative evidence pertaining to non-Euro-American cultures, transgender individuals, ambisexuals, and females is more limited.&#xa0;Data from 1534 Iranian monosexual and ambisexual males and females, who varied in their gender identities/expressions, were presented in this study. Participants reported the numbers of their biological children and occurrence of same-sex attraction in eight kinship categories: brothers, sisters, nieces, nephews, maternal and paternal male kin, and maternal and paternal female kin.&#xa0;Cisgender androphilic males were more likely to report that a maternal and paternal male relative was same-sex attracted compared to cisgender gynephilic males. Compared to cisgender androphilic females, cisgender ambiphilic and gynephilic females were more likely to report having a same-sex attracted female relative on the maternal side of their family. Also, cisgender ambiphilic females reported having more same-sex attracted sisters. No significant finding for other kinship categories and other groups was found. Ambiphilic and androphilic males, cisgender and transgender, reported fewer offspring compared to cisgender gynephilic males. In females, only transgender gynephilic females had fewer offspring compared to cisgender androphilic females.&#xa0;This study conducted in Iran, a Middle Eastern country, provided empirical evidence for familial clustering of same-sex sexual attraction and reduced reproductive output in same-sex attracted males and females with diverse sexual orientations and gender identities/expressions.</p>