This rule states that by dividing your own age by two and then adding seven you can find the socially acceptable minimum age of anyone you want to date. So if youre a 24-year-old, you can feel free to be with anyone who is at least 19 (12 + 7) but not someone who is 18.

Is it okay for a 29 year old to date an 18 year old?

Yes, its legally permissible for a 19-year-old and a 29-year-old to date each other, or to date (have sex with) anyone 18 or older (in most states).