Discrimination against employees without kids?

One thing that i've really noticed in most workplaces i've worked in is that too often it's the people with kids that get the best shifts and often enough it's those without kids who are forced all the time to pick up the crappy shifts (usually anti-social shifts) and pick up all the work that hasn't been done as a result of all the parents having to go because of "parental responsibilities"; made to work harder. I've even had older employees often enough try to lecture me telling me that i'm young and i'm fitter and that I have it easy because I have no kids.

It feels like sometimes i'm missing out on certain benefits because I don't have any family responsibilities/kids. If I was thanked or asked to pick up extra responsibilities maybe it wouldn't annoy me, but it seems to be standard practice now.

I'm not anti-family or anti-child, but it just feels like all the time because i'm a twenty something, relatively fit single male with no girlfriend that i'm able to pick up after everyone.

Anyone else have experience of this?