Sometimes it may be that the parents have been involved in their kid's lives so much -that they forget there are other topics out there, LOL!
Maybe the next time someone gets on a conversation about their kids you can snag on something else in the sentenc ("Oh, speaking of movies, have you seen?....") and get a conversation going that
you can be involved in.
Most of us parents actually
want some adult time, but it is just hard to get the mind in "relax" mode. If you give some of your childed friends another topic to hop on - they might be very thankful!
