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 sexual orientation via the fraternal birth order effect (for example, homosexual men with no older brothers) owe their homosexuality to other causes such as certain polymorphic genes (colloquially called "gay genes") or prenatal hormone levels during fetal development. Both direct and indirect evidence have demonstrated that the mechanism by which the fraternal birth order effect operates is prenatal in timing and biological in nature, rather than postnatal in timing or psychosocial in nature. Indirect evidence was found first when it was discovered that the fraternal birth order effect interacts with birth weight. Then, Bogaert (2006) produced direct evidence that the