I wonder about this myself sometimes. I pass 100%, even pre-t before I knew I was trans. Basically, if I was a cis gendered female, I'd probably be pissed, but instead I'm about as happy with it as I can be considering where I'm at in my transition. A-cup chest, extremely deep voice, large hands, broad shoulders. My most feminine feature is my butt, and I got that 100% from my father. He's got a bubble butt and my moms is flat as a pancake. Maybe you just got lucky. That's how I see my situation. My mom was flat chested before she got a boob job, my grandma has a very deep voice (mine is naturally deeper tho, she's been smoking cigarettes for 50+ years, and my great grandmother was an Olympic athlete. All luck and genetics here.