I mentioned consent to cover 18+ "kids". What I said is that if they know about it it's always ok (because they're consenting, so there's definitely no issue.). If they're over 18 and they don't consent, I feel like that should be illegal, but I don't know for sure. If they're under 18, I'm pretty sure they don't need to consent, since parents can basically make them do whatever.
Not certain on any of that, though.