In the world I would create, boys would be trained early to eat their own semen.
As soon as she knew her son was orgasmic, a mother would become involved. She'd lovingly milk his young penis until he ejaculated and then feed him his cum from her fingers. Later, she'd bring him to mate with her and expect him to lick her after he was finished.
This theme is in my story Birthday Boy. It pervades my fantasies.
Imagine if every teenage girl knew she could sit on her lover's face after they copulated and he'd lick her clean.