Sam Sheen, daughter of Charlie and DENISE RICHARDS, turned 18 in March . . . and yesterday she announced in an Instagram post that she’s on OnlyFans.

Charlie doesn’t seem to think the fact that his home was once a popular drug den (slash) sexual oasis featuring a rotating cast of porn stars has anything to do with how his daughter turned out.

Instead, he blames Denise. He says, quote, “[Sam] is 18 years old now and living with her mother. This did not occur under my roof.

“I do not condone this, but since I’m unable to prevent it, I urged her to keep it classy, creative and not sacrifice her integrity.”

But Denise says, quote, “Sami is 18, and this decision wasn’t based on whose house she lives in. All I can do as a parent is guide her and trust her judgment, but she makes her own choices.”