Do you have any sort of actual evidence to support this? (Actual evidence, not anecdotal stories about how somebody with a kid made you do more work on a project once)
So at my company there is a very strict policy about this, and it gets followed to a T.
I have worked at a place where I got the support pager on a holiday because I was single. I have also had to do support in the middle of the night because the person with children didn't answer because he set the volume low (so as not to disturb his wife) and didn't wake-up.
Anecdotally, they also seem to get sick more (kindergartens as vectors for spreading flu? sleep-deprivation lowered immunity? just guessing), but the first part is obviously true.