Does a smarter person have a better standard?
I dunno if I'm smarter, but here would be some good guidelines -
When someone should have sex -
1. The body (Both brain and endocrine system) are capable of performing the act. That means post pubescent. Brain isn't even done cooking yet before then. Pubescence IS sexual maturity, by nature. Sex before that time cannot end in sexual release, and serves no purpose to the prepubescent either physically (Can't get pregnant) or emotionally. (No hormone dumps yet.)
2. BOTH parties involved in sex must be capable of financially and emotionally supporting the existence of another human being (A child) apart from themselves ALONE, without the sexual partner in the picture.
3. There are dozens of reasons why
incest is bad. Genetics, abuse of power, (You can't be the primary caregiver and authority over a child and claim that their ability to consent, and
likelihood to consent wouldn't be bent toward satisfying the desires of said ultimate authority figure.) social stigma, physical damage (I'd hate to even
speculate what damage a 200 pound adult male with an 8 inch penis could do to a child's vagina or anus.)
That would be my bare minimum.
BARE MINIMUM. My default answer without debate would have been unrelated genetically (And let's not fuck around, unadopted as well. I'm irritated that I even have to say this.) and 16 or so, maybe 20 or 30 years ago, but nowadays I'd semi jokingly say 25. Having a not overrun credit account might also be a good indicator.
Personally, I think any woman under 25 is fucking insane and should never get closer than Tazer range outside of a group meeting.
None of this accounts for people of the same age. Two twelve year olds wanna play "Hot Dog In Bun" there's not much you can do about it apart from explain why it's a bad idea. Of course, they're already fucking idiots full of fuck hormones, so likely they won't listen. Keep them physically separated and well educated and hope for the best.
You don't fuck prepubes.
I don't fuck anyone but my wife.