50-50

There is a thought in modern psychology that a persons personality is 50% nature , 50% nurture. I think the same is true about tennis playing ability. Some people are just not born natural athletes. They can work their tails off, but they have a physical limit to how well they can play. But some people are born with tennis in their blood. They have the right coordination of fast-twitch muscles, hand-eye coordination, and core strength. How hard they work at is up to them. So there are many different kinds of players. You get the kid who has always been one step above the competition while slacking around at practice, or the kid who isn't the natural phenom but knows if he works hard enough, he just might get that shot at glory.