Originally Posted by
asking
No one's sexual identification is clearly expressed until about age 5. So whether you are born gay or straight or it develops sometime during those 5 years would be hard to pin down, but most researchers are looking at what happens in the womb during human development, not at what happens to toddlers.
Likewise, by the way, just for the record, human embryos do not all start out female and then become male due the influence of testosterone. We start out with no sex organs at all -- just as we have no kidneys, liver or any other organs. Early embryos have no testes, ovaries, or external genitalia and are described as being in the "indifferent stage" until about 7 weeks (9 weeks to a doctor).
Human embryos BEGIN to develop male or female organs between days 50 and 70 after fertilization, after which they are partly differentiated and everything can continue to develop. The Y antigen gene on the Y chromosome induces the development of the testes. If there is no Y chromosome, the embryo normally develops as a female, although there are exceptions. For example, the over expression of a single gene (WNT-4) can result in an XY female. That is, an individual who is genetically male but fully female otherwise. At about 20 weeks, the testes begin to secrete testosterone, which induce the development of the penis and scrotum. Intersex individuals--in which one sex is not easily assigned-- make up about 1 in 2500 births.
None of which has anything to do with gender identity, which as I say, finishes developing at around age five.