Dee, I think that gets very far into a territory that none of us (unless anyone here has been through it) could possibly understand. It has to do with genetics, and a host of other topics that are far far beyond the scope of this forum.

Minor changes to enhance our looks is something we all do every day. Major changes have basis in a variety of areas as we've already discussed, whether it be cultural, due to illness or trauma, or for other reasons. Gender re-assignment is a completely different matter, with a wide variety of reasoning and philosophies for and against, and is best discussed elsewhere.