We can't know for certain what causes who we are, but we know our wants, and we can find words that apply to them. Therefore, I don't know why you and I want to be female, but the fact that we do, means the word transgender applies to us. As someone who has dealt with gender dysphoria their entire life, you can trust my authority (just kidding).
Personally, the cause of my gender doesn't make a difference to me. My gender simply dictates some of my preferences, and since my preferences are no better or worse than anyone else's preferences, I see no reason to attempt to destroy this part of myself. Life is prosaic enough, so why make it even more mundane?
Our existence is brief and arduous, so please don't waste time on questions that can't be answered and things that can't be changed, and make the best of your life.