Article reorganization 

There is a confusion between the different definitions of heterosexuality.  I think this article should be worded more like the homosexuality article, which distinguishes between homosexual orientation and same-sex relationships.  Likewise, there needs to be a distinction between people with a heterosexual orientation and people who have sexual relationships with people of the opposite gender.  I think if we reorganize the page like the homosexual page this distinction would be more clear.  For example, it would make clear that reproduction results from heterosexual sex, not from a heterosexual orientation.  On the other hand, the causality section is mostly about the development of a heterosexual orientation.  That crucial element isn't clear. I am going to start reorganizing it like the homosexuality page.