>> people generally don't like to listen to stories that suggest that nurture and hard work aren't as important as they presume
Having grown up in australia but living in the us, this attitude is very american. It's quite funny to see when you don't grow up thinking it. I married into a very athletic family and have a child who is a precocious athlete. Many parents ask us what training regime or practice sessions we do. The answer is nothing. People don't react well.
So, what do you tell children that do well/poorly?
If you work at it you can get better. It's true in both cases. Getting better and getting as good as the very best are two very different things. One is about you. The other is mostly about others.