Care and Feeding Photo illustration by Slate. Photo by Getty Images Plus. Care and Feeding is Slate’s parenting advice column.  Have a question for Care and Feeding?  Submit it here . Dear Care and Feeding, My wife and I have a wonderful 7-year-old son, “Luke.” He has always wanted toys like Barbies, prefers princess movies to superhero movies, and dotes on his little sister, making up fairy-tale games for her. I’m proud of what a kind, sweet boy he is. It’s other people I have a problem with, namely, my brother-in-law and his kids. Recently, we saw his cousins for the first time in a while (we all live far apart). My nephew (8) and niece (10) made fun of Luke for being “so gay” and “a girl,” which I only found out when I went upstairs to fetch the kids for a meal. I told them (quite sharply, but not in a yell) that neither of those things are insults and they were being very silly, and took Luke away to be with his sister and the other adults.…