I know that my husbands parents and his aunt and uncle do not like children. It is odd as they all had them themselves! I think children can be very tiring and perhaps that is part of teh reason why they don't want to see much of them.

My first child's grandparents on her father's side were exactly this way (they are, however, now deceased). They weren't very warm people at all and could never relate with any child, it seemed like they didn't like kids that much and maybe this was the case with them.
I didn't bother with them since after realizing how they were towards their grandkids.