Its a mix "There is evidence that hormonal effects on the mother's nervous system during pregnancy may play a role in assigning gender identity. Those receiving lowered amounts of hormones from the parent may give rise to the child having problems identifying with their gender role. Normal amounts are thought to ready the child to receive the definitions and inputs on masculinity and femininity from the parents (Grellert et al. 1982). Thus, the gender role is a combination of both the biological and the social, rather than a product of one or the other.
It is in the period after infancy, when the child begins to develop language skills, until adulthood that the child begins to undergo very different processes. These processes are extremely culture-bound. It is through these processes that the child begins to organize how s/he will deal with the world. There are two experiences that dominant these
years. The first is the naming of the behaviors, and adult reactions to them, specifically the sexual. The second is the continued building of gender identities based on decisions made on the maleness or femaleness of the child by adults (parents, doctors, etc.).
A wealth of studies on families and twins show heredity accounting for between 30 and 70 percent of the variation in personality traits among people, leaving another 30 to 70 percent to be accounted for by the environment. Research shows that shared environmental factors (things siblings have in common), such as socioeconomic standing and what school
you attended, play only a small role in shaping basic personality traits. It is the environmental factors that siblings don't share, such as one's birth order in the family to a person's unique life experiences, that are the most influential in forging personality.
In a study by Hamer (http1), he linked male homosexuality to a stretch of genes on the X chromosome. A number of studies had shown that homosexuality is partly heritable, half of the identical twins of homosexual men are themselves homosexuals, proving such genes might exist. But the evidence also hinted that homosexuality is a complex trait, arising from the interaction of a number of genes and environmental factors. Hamer turned up the first evidence for what others would dub the "gay gene" in a study looking for the genes that caused certain people to be more susceptible to certain cancers. Hamer had gone fishing in the DNA of 40 pairs of homosexual brothers. His strategy was simple: siblings share, on average, half of their DNA. So if a particular gene did influence homosexuality, that gene would lie in the half of the DNA they have in common. With data from one pair of brothers, Hamer could narrow his search for a homosexuality gene from 100,000 genes to only 50,000 or so. With data from additional pairs of homosexual brothers, he could collect enough genetic information to close in on areas of overlap among them. In practice it wouldn't be so straightforward. It was unlikely, for instance, that every pair of brothers would share any one "gay" gene, given the earlier genetic studies that found no simple pattern of heritability. So Hamer would look instead for statistical anomaliesóbits of DNA that were shared by more pairs of brothers than would be expected by chance."