Since her father is gay he's always lavished her with brand named things and stick their noses up at the lesser things in life? Really? Do you think all gays do this? That's an amazing generalization.
I know women who are clothes horses and there is nothing gay about them or anyone in their families. When first graders talk about name brands I haven't even heard of, I wonder what kind of girls they will grow up to be. I went into a store one time and a mom and two of her teens were trying to buy a boatload of clothes, and mom pulled out credit card after credit card trying to find one that wasn't at its credit limit. All I could think was "Poor Dad!". He works hard and they just spend, spend, spend.
I don't actually look at buying something that is MORE expensive just because it is a brand name as a particular pleasure, A., and I would like to tell you that you shouldn't either. And it really seems to me that you look down on your cousin's father because he is gay as much as your cousin looks down on "lesser things in life". I am trying to figure out if you think it's also her father's "fault" as a gay man that she doesn't like redheads.
Your cousin just sounds like a spoiled brat who doesn't have enough to think about that matters, and her father sounds like a father who has doted on her to try to give her what he likes - "the best" - and has done a poor job of teaching her what is important in life. Where is her mother in all of this? Who has taught her respect and responsibility?
Your cousin's attitude about what she would do if she had red-headed children just sounds bizarre. I don't know who really took care of this kid during her formative years, but I doubt that they taught her much about the golden rule, and that's a shame. I sure hope she doesn't have red-headed children.
At any rate, perhaps you should think twice about the idea that someone would raise up a child this way because they are gay. It is because they are irresponsible parents. And there is plenty of that kind of parenting going around without sexual orientation playing a part in that.