Indeed. It's hard to believe that until relatively recently people thought that sexual attraction was fundamentally based in biology rather than identity.
Trans people are part of biology. It's what happens when you are exposed to cross-sex hormones.
Personally, I tend to view (my own) transition as embracing an intersex condition with medical intervention.
Not implicating anything in particular, other than that biology is ridiculously complex. I can only speak from personal experience.
Before I transitioned, I noticed there was a pattern in my life where cis lesbians were interested in me, I've even dated a lesbian cis girl _as a boy_ when I was about 15 or something like that.
Biology is very strange.
I personally use the word "soul" for this kind of stuff. But that's nonsensical in the end.