Another prevalent theory has to do with certain patterns in a person’s family back­ground. Psychoanalytic theory implicated both childhood experiences and relation­ships with parents. Sigmund Freud (1905/2000) maintained that one’s relationship with one’s father and mother was crucial. He believed that in "normal" development,

we all pass through a “homoerotic” phase. Boys, he argued, could become fixated at this homosexual phase if they had a poor relationship with their father and an overly close relationship with their mother; the same thing might happen to a woman if she developed envy for the penis (Black, 1994). However, this particular family dynamic is occasionally present in the family backgrounds of both gay and straight individuals and is absent in the family life of many homosexual individuals. Bell and his colleagues (1981) concluded that no particular phenomenon of family life could be singled out as “especially consequential for either homosexual or heterosexual development” (p. 190)—a conclusion supported by subsequent research (Epstein, 2006).

In the next section we discuss the most relevant and current research that attempts to understand the biological factors that may influence sexual orientation.