Desire, of course, isn't the same as consent, so to me that's a gray area... but a male animal jumping on somebody and initiating it? Doesn't sound like animal abuse to me.
again we're brought to minors. if a 10 year old wants to jump his 20 year old teacher he is not capable of giving consent, legally. it would be rape on her end. same deal here. you can use it with a person on drugs too, the situation doesn't really change. there's no reason why it wouldn't be considered rape.
the uncle/niece situation though is definitely a weird one because of conditioning more than anything else. it's not even the relationship as much as the older party can abuse their authority to create a setting where they're gifting the kid to make them 'fall for them.' this is a definite known form of abuse, but if you look at the adult equivalent of it (which is really no different) then it's still legal there. so while it can be messed up.... the law really shouldn't involve itself too deeply there, if at all.
--
The King Wang.
Listen up Urinal Cake. I already have something that tells me if I'm too drunk when I pee on it: My friends. - Colbert.