The interest for the sport depends on the size of the brain

 You are or not an athletic and sports person might be tied to the size  of your brain.
To analyze the brain of rodents raised during generations to select those " lovers of the exercise ", they observed that his average brain had a size 13  % more of the normal. In this zone of the brain there reside the centers of motive, auditory and visual control of the systems. In addition, it is essential for the learning with reward and the motivation.
It is possible that the individual differences in the predisposition towards the exercise could be related to the size of the average, and enclosed brain that the volume of this zone could inherit from parents to children.