In this report (Volume 17, Number 2), J. Michael Bailey and colleagues bring the latest science to bear on these issues, providing a comprehensive review of the scientific research on sexual orientation that corrects important misconceptions about the link between scientific findings and political agendas.

Based on their review of the latest science, Bailey and colleagues draw several conclusions about the nature of sexual orientation:

Across cultures, a “small but nontrivial” percentage of people have non-heterosexual feelings. The specific expression of sexual orientation varies widely according to cultural norms and traditions, but research suggests that individuals’ sexual feelings are likely to develop in similar ways around the world.

Men’s and women’s sexual orientations manifest in different ways: Men’s sexual orientation is more closely linked to their patterns of sexual arousal than women’s sexual orientation is.

Various biological factors—including prenatal hormones and specific genetic profiles—are likely to contribute to sexual orientation, though they are not the sole cause. Scientific evidence suggests that biological and non-social environmental factors jointly influence sexual orientation.

Scientific findings do not support the notion that sexual orientation can be taught or learned through social means. And there is little evidence to suggest that non-heterosexual orientations become more common with increased social tolerance.