Here’s an article from Todd Hargrove explaining why and how our skeletal structure affects our movement and why an individualised approach is so important in exercise, rather than forcing each body into ‘some Platonic ideal’: ‘Optimal alignment or posture for a certain function is partly a result of having as many joints in neutral as possible at any one time. And the shape of the bones will determine how many of your joints you can keep in neutral at the same time in a particular functional task…we should be very wary about anyone dictating to us what proper form is in regard to a particular activity without considering our individual variations in structure.‘ Full article here
Here are some very clear illustrations of anatomical variations in pelvic and femur structure- a squat for these two individuals will (and should) look very different:
Images from here