I put this idea forward in another thread, but wanted to give it its own thread before discussing it (to avoid derailing the other thread).
What I said was that the two most dangerous "groups" of guests in the park are teenagers and parents of small children.
Teens, well, that's the obvious one. Many teens lack the experience or discretion to act in the interests of safety. Decades of DUI accident records can't be wrong. Obviously not ALL teens are dangerous, but as a group, they are definitely leaders in unsafe behavior.
But many people will be surprised by the "parents of small children" one. Why do I say that? Simply: they are so singularly focused on their kids that they do so at their own (and everybody else's) peril.
Example: Parents are so focused on their kids' safety that they actually endanger themselves and everyone else. This happened all the time at Indy. Guests board the vehicles, and they're supposed to sit down and buckle up. The way Indy works, once the guests are seated, the car is released to the next station hold to check seatbelts. Well what happens is a family boards the vehicle, everyone sits down, the CM releases the vehicle as soon as everyone is seated. However, the parent no sooner sits down than they stand back up again to check their kids' seatbelts because they don't trust the CMs to do it. Meanwhile, the vehicle lurches into motion, throwing the parent off balance (and sometimes into their kids' laps), the CM sees them standing, calls a hold on the vehicle, the vehicle stops suddenly (because it cannot continue forward with a standing guest), and the parent then falls forward onto the heads and shoulders of the row in front of them.
Another example: Parents are so focused on their kids' experience that they endanger their safety to guarantee a good time. This happens pretty much at every attraction that has a height requirement. Parents refuse to believe that height restrictions have any basis in actual safety, so they actively participate in trying to get undersized kids on rides which are not appropriate for them. Or they take their kids on rides that are too intense for them, hoping it'll "build character". See the case of the little kid that died after going on Mission Space.
Perhaps others on this board care to confirm or refute my arguments. Please keep it civil, folks.