Same dates and horoscopes. Anyone else?

My mother's birthday is on February 13th and my father's on May 13th. They're no longer together and divorced when I was four.

My birthday is on December 18th and my brother's on March 18th. My brother is a Pisces, but I have a Pisces moon. My father's second wife also had a 13th birthday, and I think the third did too.

Isn't that strange? Does anyone else have these things?