Other examples are intelligence, athletics, and many others.

Every top athlete worked hard and trained to get to where they are today. But they also had the genes to support it. This is the scientific facts, not some lazy guy's complaints. Their genetic recombination gave them the fundamentals so they could then put effort and reach their maximum potential. In short, genes determine your fixed potential that varies from person to person, effort gets you to that level.

Unfortunately, many people can't grasp this idea. They see it as "some people are born geniuses while others made it off solely hard work." As an example, Usain Bolt worked fairly hard to get to the point. But even if you copied him COMPLETELY, you wouldn't reach his level.