1. Body structure proportion: The body structure proportion such as head-to-shoulder ratio, waist-to-shoulder ratio, slender limbs and relatively thin joints is natural, but it can also be improved through exercise.
2. Muscle shape: The shape and symmetry of muscles are basically innate. For example, whether the abdominal muscles are symmetrical or not, some abdominal muscles are innate, and no matter how you practice, you can't change them. So some people are symmetrical and some people are asymmetrical.
3. Congenital muscle potential: If you have higher muscle growth rate or faster recovery rate, then you may perform better in fitness.