Sexual attraction existed in different cultures is controversial. Pheromones have been determined to play a role in sexual attraction between people. They influence gonadal hormone secretion, for example, follicle maturation in the ovaries in females and testosterone and sperm production in males. Research conducted by Donald G. Dutton and Arthur P. Aron in the 1970s aimed to find the relation between sexual attraction and high anxiety conditions. In doing so, 85 male participants were contacted by an attractive female interviewer at either a fear-arousing suspension bridge or a normal bridge. Conclusively, it was shown that the male participants who were asked to
Fraternal birth order and male sexual orientation fraternal birth order (or the underlying variable it reflects) may be the first universal factor to be identified in development of same-sex attraction in males. Bearman and Brückner (2002) argued that studies showing a fraternal birth order effect have used nonrepresentative samples and/or indirect reports on siblings' sexual orientation. Their analysis, focusing on opposite-sex twins, did not find an association "between same-sex attraction and number of older siblings, older brothers, or older sisters". A study by Francis (2008), using the same Add Health survey but with broader analysis, saw a very weak correlation of male same-sex attraction with having multiple