Is it normal to do this with your cousins?

When I was younger (around 12), my 2 cousins and I (we're all girls) let our curiosity and new hormones get the best of us. We would compare our bodies and make up inappropriate games that would have something to do with sex, like a nude game of house(and we would hump each other etc.). We weren't really sure exactly what we were doing. But the pleasure made it hard to stop. We would do this a lot, and it became a habit. A hard one to break. As we got older, and knew more about what we were doing, we did more things, going farther and farther each time. Even now sometimes, when I can't control myself, we do stuff together. Is this normal?