acceptance in past cultures

I will be addressing this post separately in my capacity as a moderator, but here I will mention a couple passages from the Milligan article:

First, this is self-explanatory:
"A Roman Citizen was allowed to exploit his own slaves for sex, no matter the age or circumstances of birth."

Second, this makes it clear that the practice was common and accepted:
"The term, puer delicatus or deliciae (meaning sweet, dainty) is often applied to child slaves used specifically for sexual gratification and companionship."