Is running ability down to effort or DNA? And can it be proved?

If you’re really serious about competitive running, there are companies that test your DNA to determine your sporting potential. But does it work?Growing up, I was always the dumpy, unsporty one. Matt, my older brother, was the skinny one who did the running, jumping and anything requiring quickness and coordination. He seemed to excel with ease while I laboured away on a sluggish course towards sub-mediocrity. This pattern lasted until our late teens when Matt, being older, beat me to boo