All my kings only have sons

[Tricky Lady]

I have noticed that in my last 9 or 10 games, my kings never get any daughters anymore (except the starting princesses). It doesn't really bother me (it's quite OK to be sure that you'll always have an heir), but I was wondering if this is normal.
Has anyone else seen this too?

[Goofball]

It has happened to me before. Just coincidence.