It sounds as if you are trying to equate being gay to a learned behavior. If that is true how do heterosexual parents raise gay children, however, here is what you asked for.
According to current developmental psychology, medical studies and reports over the past 10 or more years, the research indicates that the chances of a child who is raised in a gay or lesbian household will be gay is 10% or less.
Which is about the same odds that a child raised by heterosexual parents will be gay.