I don't think anyone is obligated to have children, and there is too much pressure (a lot of times from yourself) to "pass on" your genes and carry on your family name, which in the larger scheme of things is actually rather nonsensical. If you believe in evolution etc. then not only are we related to each other on a very fundamental level, but also connected to every other living thing on the planet. "Life" will carry on just fine without your particular arrangement of genes/DNA. Also sometimes, the decisions people make to NOT have children are a lot better than the decisions people make TO have them.
Reproduction is not about your family tree, it's about survival of the species (which is really not under threat!). It's just as valid to play a "supporting" role in that as a reproductive one. There are plenty of examples of this in nature. Not everyone will, or has to reproduce.The last thing I would want to do now is have children, and if the issue of children did arise, I would rather adopt and help a child that is already here.