I had also encountered same problem. Here are two questions Q.1, Q.2. I found the first question to be interesting and deserves more attention. However, the second question was simply a duplicate problem and still received good response rather than closing it.
There are quite a few users who use photos of their children as avatars. A prime example is one of the Community Managers. There's nothing wrong with that :)
If you do see a user who claims to be younger than 13 years, or see an equivalent statement about their current grade (pay close attention as those might differ per country), they're not allowed to use ...
Quoting @Gerry Myerson:
This site is run by people, not machines.
It's inevitable that someone would meet two "extreme" ends.
This makes it clear that MSE is a very large and diverse community. You can have an extreme set of varied opinions expressed by people here. The denial of the flag was only a by-product of this diversity and people's ideas ...