I am the black sheep of the family. No one has it except for me. I have a twin sister but we're polar opposites (personality and looks wise). I come from a Cuban family so EVERYONE is so loud and extremely outgoing. I don't know how I ended up like this. :/
My older brother definitely doesn't have it. He's the funny one with the personality that draws people in, and I'm the one that's easily overlooked. This fits into why I don't even bother to attend family gatherings anymore.
My brother doesn't enjoy being around or talking to people, but he isn't socially anxious. He just doesn't like most people. My younger sister is kind of shy and quiet, but I don't think she has SA. And my older sister is really outgoing.
My younger brother has it, and can't work because of it. My two older brothers act outgoing, but i'm sure they're masking insecurities as they're at times either over-confident and outgoing, or acting as if the world is against them. They both get really over-defensive at the slightest thing, so its impossible to discuss our problems with each other.
When I think back, i'm sure my dad had it, though I never thought about it when he was alive (he died 5 years ago this month). He brought us up to be quiet and to never discuss our feelings, and whenever there was an argument he would simply go to bed and refuse to get involved. My mum is outgoing, but went along with how my dad wanted to bring us up. I'm sure this is what has caused my SA - even now it is at its worst whenever I see a member of my family.