Have Kevin, Grant & (If he's into this sort of thing) Brandon engage in mischief (Give them the Mischief Trait if neccesary) by sneaking into Bars, Night Cubs & Strip Clubs (Particularly the one Kevin's Mom works at which will be the one Ari Maram owns with a friend as the bouncer) as well as other typical PETTY teen crimes

If possible, get Kyle from DDSims as he'd be a PERFECT fit to join Kevin, Grant & Brandon to make a Quartet as he demonstrates very clearly in this video

And have them all attend Copperdale High School where they'll learn Sex Ed from Kris & her colleagues (And teach THEM a thing or two as to whatTHEY have learned 🤩😍)