Paper investigates non-biological aspects of sexual orientation development.
Yin Xu et al., "Early life conditions and adolescent sexual orientation: A prospective birth cohort study," Developmental Psychology 55, no. 6 (2019): 1226.
Research suggests that genetic factors explains approximately one third of the variation in sexual orientation (Bailey et al., 2016). Thus, most of the differences between people in their sexual orientation are due to environmental factors (often nonshared) pointing to multiple etiology.