I learned pretty early on that my behavior had to be masculine or else. I have clear memories of when I was 4 or 5, being yelled at by my mom for the way I would sit, she would tell me that I wasn't a girl, so I shouldn't sit like one. She doesn't remember this actually happening though, weirdly. There's a lot about my childhood that I found traumatic, that my mom just can't place happening, or so she says. But I remember every time where I did something that was stepping outside the lines of where I was supposed to be with regards to Gender, and getting told I wasn't a girl. Eventually my mom came to accept that I crossdressed at home, which was fine with her so long as I wasn't a girl. And that lasted from about 4th grade to 7th grade, when I asked her if she would buy me my own clothes, and she informed me that I wasn't a girl, so she shouldn't be wasting money on clothes for me that were for girls. And that shut me up through a lot of high school, though it was something I was always thinking about. Then eventually in college, I finally started getting the courage to live my life how I knew I wanted to live, and started to assert that I was female.
Of course I got the whole "but you never acted female growing up" schtick too. But I knew it was a lie. And I knew how much of my habits were born out of repression, rather than expression. So what if I played the part well, y'know? I was still acting.
There's so much to sift through when you transition about what is you, and what is society's pressure on you it can be really confusing at times, and I haven't found parents to be the most objective or useful sources for that debate.
I'm still trying to articulate what female means to me. I don't think it's as easy as the things you do, or how you look. It's something deeper than that, that does feel inate. But I don't really know how to explain it's differences to maleness without going to surface things. I think most GGs would have the same problem though, if you asked them to define femaleness, at least if they were really thinking about it.