There's no doubt they had sex in The Naked Time.
But Tasha was under influence.
She seemd to regret that at the end opf the episode: "It never happened!"
Roddenberry was portraying the future as sex-liberal, but I'm not sure this is liberality.
OTOH Data is clearly immature at that point. He could be argued to be incapable of understand his actions. He annoyed Picard with embarassing questions often.
Edit: given the occasional truculence of the moderators I've seen around here I half-expect this thread to be deleted or closed on sight. If so, oh, well.