Sure, like that. "Very few angels engage in sexual activity. It's seen as superfluous." Like way, way back in the day when there was very little to do, before Lucifer fell, sometimes a few angels did the nasty just to see what it was like. But after that it was all 'prophecy this' and 'prophecy that' and Heaven became very, very structured and angels did a lot less rejoicing and praising of the Lord God their Father and a lot more fighting and guarding. But, then, that was what God had supposedly commanded of them. No more celebration after Lucifer fell.

Castiel hardly remembers the times from before Lucifer's betrayal. He'd been very, very young. Most of the younger angels didn't even know much about their version of sex, but Castiel had always been abnormally (discouragingly, his superiors told him) curious before the fighting began and made a point to find out.