Across cultures, 2% to 10% of people report having same-sex relations. In the U.S., 1% to 2.2% of women and men, respectively, identify as gay.
Despite these numbers, many people still consider homosexual behavior to be an anomalous choice. However, biologists have documented homosexual behavior in more than 450 species, arguing that same-sex behavior is not an unnatural choice, and may in fact play a vital role within populations.In a recent issue of Science magazine, geneticist Andrea Ganna at