Adding to my previous post... It's worth pointing out that there are perfectly legitimate reasons for a couple to choose not to have children, beyond "ski vacations."
* Finances; It often takes two working adults to keep a single roof over their heads. Kids are expensive and the cost of childcare can often be more than what either parent earns. It is common for a couple to find it financially unreasonable to start a family.
* Careers: Being effective parents is a huge time commitment. If two folks have careers that demand 60+ hours a week, one would likely have to cut back should they choose to have kids. Are we saying that folks are expected to give up careers to fulfill some unwritten duty to start families?
* Health: If one or both partners have health issues that demand time, increase fatigue, etc., adding children (which takes a ton of energy) might not be feasible.
I love being a grandfather and I absolutely adore my granddaughter. However, my son and his partner would not be able to effectively raise her without the support my wife and I provide (such as nearly full-time childcare while the parents work). They do not earn enough money to support a family and neither is finished with school. I very much respected (and agreed with!) their choice to not have kids. ("Maddie" was no planned...)
Hard work builds character and homework is good for your soul.