Perhaps I am overthinking the question but this is why I believe that I like to crossdress. I started dressing up in my older sister's clothes when I was a teenager for the sexual gratification. It felt so wonderful! I used to think that girls had it so nice, to be able to wear sexy lacy underwear, bras for their boob and sexy clothes while us guys had to wear plain old cotton underwear. It just wasn't fair at all!
I guess deep down, I think it's because I admired my sister so much and she was and still is a very beautiful looking lady. I wanted to be like her, beautiful, sexy and confident.