Fake sex as kids?

When me and my twin sister were young (like 5 years old) our friend from church taught us to play "house" and we would have to be husband and wife and kiss eachother (with our hands covering our mouths) and pretend to have sex even though none of us really knew what sex was. We thought you just laid on top of one another lol. But in the following 5 years or so me and my sister would continue to do it very frequently, also making our dolls and stuffed animals have sex. I thought it was normal until we invited a friend to do it and she got freaked out. We stopped doing it soon after that.

It's so weird because we reflect on our past alot but neither of us have ever brought this up.