Maybe you missed the point. The poster said marriage at 12 used to be legal and we said slavery used to be legal also but that didn't make it right. I don't know of anyone who would equate sex and slavery.
And why was it wrong for 12 year olds to marry in the early 1800s and before. And how do you equate that with slavery?
We're way off track already, but surely you're not blaming sex with 16 year olds on Kinsey, or are you?