While recent research has advanced our understanding of asexuality, very little effort has been devoted to examining biomarkers and possible prenatal correlates of asexuality. In response, we recruited a large international sample (N = 1634 women and men) to explore associations between sibling composition and asexual sexual orientation (n = 366) and to replicate previously reported sibship effects in individuals with a same-sex attracted orientation (n = 276) and bisexual sexual orientation (n = 267) compared to heterosexual individuals (n = 725). Our analyses used two of the most recent statistical approaches that attempt to disentangle older sibling effects from family size effects (Ablaza et al., 2022; Khovanova, 2020). We found that higher overall number of siblings (female fecundity effect) predicted higher probability of asexuality in men and having fewer older sisters and being an only-child predicted higher probability of asexuality in women. Regarding the same-sex attracted orientations, higher number of older sisters increased likelihood of being a gay man (sororal birth order effect). Having fewer older sisters was associated with bisexual sexual orientation in women and higher overall number of siblings predicted increased likelihood of bisexuality in men. We did not find a fraternal birth order effect for gay, lesbian, bisexual or asexual groups using the Ablaza et al. (2022) method but the effect was significant for gay men using the Khovanova (2020) analytic approach. These findings point to potential sibship-related contribution to development of asexuality in women and men but future studies will need to replicate these results and articulate potential underlying mechanisms.

虽然最近的研究加进了我们对无性恋的理解，但很少有人致力于检查无性恋的生物标志物和可能的产前相关性。作为回应，我们招募了大量国际样本（N = 1634 名女性和男性），以探索兄弟姐妹构成与无性性取向 （n = 366） 之间的关联，并复制先前报道的同性吸引性取向 （n = 276） 和双性恋性取向 （n = 267） 个体与异性恋个体 （n= 725）。我们的分析使用了两种最新的统计方法，试图将哥哥姐姐效应与家庭规模效应区分开来（Ablaza 等人，2022 年;Khovanova，2020 年）。我们发现，兄弟姐妹总数较高 （女性生育效应） 预示着男性无性恋的可能性更高，而姐姐较少和独生子预示着女性无性恋的可能性更高。关于同性吸引的取向，更多的姐姐增加了成为男同性恋的可能性（姐妹会出生顺序效应）。姐姐较少与女性的双性恋性取向有关，而兄弟姐妹总数的增加预示着男性双性恋的可能性增加。我们使用 Ablaza 等人 （2022） 的方法没有发现男同性恋、女同性恋、双性恋或无性恋群体的兄弟出生顺序效应，但使用 Khovanova （2020） 分析方法对男同性恋者的影响是显着的。这些发现指出了与同胞关系相关的潜在贡献，导致女性和男性无性恋的发展，但未来的研究需要复制这些结果并阐明潜在的潜在机制。