1. You're right. I used the term "mothers" because I was raised by a single mother and both the women on TV were mothers. But, all sorts of people raise children. Fathers, grandparents, relatives, caregivers, etc.
2. I definitely celebrated both of my kids. I thought they were amazing when they were born, and I still feel that way.
I once commented, in reaction to a mother who never seemed to be able to say a single nice thing about her daughter, that I believed parents ought to be their children's biggest fans, not their harshest critics. If your parent doesn't think you're terrific, who will?
3. Having one boy and one girl meant that my children were very aware of gender roles in our house. And if they didn't exist, the kids would create them. It was a way of differentiating themselves from each other. If the girl liked something, it very quickly became a "girl-thing". If the boy liked something, it was a "boy-thing". Didn't matter what the thing was, or even if it was usually labeled that way in broader society. I still remember my small daughter announcing confidently, from the back seat of our car, that, "Mommies don't drive!" Eeep. Gently pointed out to her that her mommy doesn't drive, because her mommy's eyes don't work like they should. But, lots of other people's mommies drive, and some people's daddies don't drive. Anyone can drive! Or not, as the case may be.
I suspect all siblings try to establish themselves as individuals, in opposition to each other. Gender is an easy dividing line, but one of our neighbours has two daughters... as small kids they identified themselves as the sporty one and the bookish one.