ABSTRACT

Since the 20th century, multiple studies have linked the variations in human sexual orientation, from heterosexuality to bisexuality or homosexuality, to a wide range of biological factors. However, a clear mechanism that leads to the development of these variations has not been established yet. This review consolidates various comprehensive studies on the possible biological factors in the fields of genetics, epigenetics, uterine environment, hormones, neuroanatomy, and neurobiology that lead to these variations. One intriguing question that ‘homosexuality phenotype’ faces is its ability to avoid elimination by Darwinian selection. This review tries to explain why natural selection is not eliminating the genetic factors associated with homosexuality even at the cost of the evolutionary fitness of homosexual individuals. Studies supporting certain strong candidates for alternative sexual orientation (ASO) are highlighted, which can become new research avenues for investigators in this field. Further, a novel speculation is proposed that might be contributing to the development of variation in human sexuality.

摘要

自 20 世纪以来，多项研究将人类性取向的变化（从异性恋到双性恋或同性恋）与广泛的生物学因素联系起来。然而，尚未建立导致这些变化发展的明确机制。这篇综述整合了遗传学、表观遗传学、子宫环境、激素、神经解剖学和神经生物学等领域中可能导致这些变异的生物学因素的各种综合研究。“同性恋表型”面临的一个有趣问题是它能够避免被达尔文选择淘汰。这篇综述试图解释为什么自然选择并没有消除与同性恋相关的遗传因素，即使是以同性恋个体的进化适应性为代价。强调了支持某些强有力的替代性取向（ASO）候选者的研究，这可能成为该领域研究人员的新研究途径。此外，提出了一种可能有助于人类性行为变异发展的新推测。