It puts the kid in an awkward position if they have to try to articulate that.
Or that you'll blame one of their friends for bringing up this topic.
Just assume they want to know because they are curious humans who want to learn.
Don't treat sex any differently.
But I'd do my best to show them I was asking to help rather than judge.
But the few times I asked her things, I got grilled about my motives. Extensively. And it sucked.