People who need to squat multiple times per day to poop throughout their lives have much better ankle flexibility than western office workers who spend their lives sitting on chairs, car seats, and chair-style toilets and never squat ever.

I also fall over when I try to squat flat on my heels. Friends who do yoga and friends from countries with squat toilets have no trouble with it though. All children under about 10 years old can squat just fine. Lesson: get your kids a squat toilet if you want them to have standard human levels of ankle flexibility when they grow up (also very helpful for improving jumping skill, if they plan to ever play sports). ;)