I would never call anyone in this family stupid. They are sailors, that is what they do.
I grew up with friends who started training to race cars when they were 11/12 years old. They came from a family of race drivers, and that's what they did. The same goes for farmers. My Dad started working with heavy and dangerous farm equipment when he was 12/13, because that is what his family did.
Just because you would choose not to have your child attempt this, doesn't mean there are not families out there who are more than capable of understanding the risks and allowing their children to attempt such a feat.
It's the same thing we see time and time again on this board. People are trying to fit their own standards onto someone else's life, assuming their position to be superior, when, in fact, they are just 2 differing opinions and neither one is superior to the other. In short, the parents are not "stupid."