Good question, Jillieann! I have 3 brothers, and am FtM... so I know if and when I come out to my parents, they'll be devastated at losing their daughter. But I know it's not my brothers who influenced my masculinity; my 2 older brothers are my dad's kids from a past marriage, and they live overseas; my younger brother is 7 1/2 years younger, and I was already displaying male traits long before he was born. I actually wish I had a sister... then maybe there wouldn't be so much pressure on me to act feminine. As it is, I'm now incredibly jealous of my 16-year-old, 6'4", incredibly masculine little brother.
Rafe