The "nature or nurture" debate won't be settled anytime soon, though I suspect, as in most manifestations in the universe, that human sexuality is best expressed as a continuum rather than an either/or state.  Perhaps a bit of thought should be given to the practice of dressing young boys in dresses and gowns that was once common in Western societies for over 300 years.  I am unaware from the historical record that much harm attributed to this custom can been proven.  Even Franklin Delano Roosevelt was dressed as a girl until roughly age six.