Theory: Being a great runner is from muscle memory passed down through your DNA.

Sand Dunes wrote:

You're talking about epigenetics. More research is needed.

This is in the right direction. To add...

Reprogramming resets the epigenome of the early embryo so that it can form every type of cell in the body. In order to pass to the next generation, epigenetic tags must avoid being erased during reprogramming.

In mammals, about 1% of genes escape epigenetic reprogramming through a process called Imprinting.