It's not a physical phenomenon. In my dialect, I don't usually say copycat. I usually just say copy. And for me, copycat is a noun, meaning a person who copies. Mostly children use that word.
Little league is supposed to teach kids good manners for team sports.
I think this is one of the good points and original purposes of little league. But sometimes, everyone gets a bit carried away, especially the parents. And there has been some controversy over parents forcing their children to play beyond their abilities and of young pichers injuring their arms from pitching too hard and competing too hard when they're still too young and are still growing. There's been a lot of controversy recently about ice hockey. I read in an article a couple of weeks ago in a magazine saying that they think part of the reason ice hockey has become so violent is because of expanding the national hockey league very quickly.