Children usually are proportioned to make squats easier as well.
As an adult, not being able to air squat with parallel feet isn't necessarily a symptom of bad body mechanics, muscle imbalance, or ankle mobility. It could just mean I've gotta big booty and a small head. Which incidentally, I do.
As an aside, I always found it so strange seeing men with a huge ass, and a normal sized body. Something I always associated with women, and having large hips. Sorry man!
Perhaps I should say, "Well defined"? I'm an amateur athelete, and one of my specialties is cycling. If you have proper glute activation, it gets developed. But so are my quads, hamstrings, calves, etc. I do not have very pronounced hips - my hip bones are not wide. Glutes are the biggest muscles of the body and the hardest to exhaust in endurance activities.
As an adult, not being able to air squat with parallel feet isn't necessarily a symptom of bad body mechanics, muscle imbalance, or ankle mobility. It could just mean I've gotta big booty and a small head. Which incidentally, I do.