How common is my situation?

First off, I'm 46. I had my first child, a boy, at 16 with my first wife. We later had 10 more, so I ended up with 10 boys and a girl. The girl is the youngest and is now 17 and having children of her own. I recently had a new child with my second wife (my first died in 2004). One of my older sons is now a grandfather, making me a great grandfather. My child is younger than my great grandson and great granddaughter. How common is that?