Answer: athletic ability
Some things are 100% genetic based whilst some are 100% environmental based and some are a clear combination of the two.
Things like our color of eyes, blood type, quality vision, teeth, and certain diseases are purely genetic based. Children tend to get the eye color based on what they receive from their parents.
Whereas, what kind of language, religion and social traits you adapt are purely environmental based.
Traits that are a combination of both genetic and environment are height, weight and diseases.