Do you mean get married or have kids? Only thing I can thing I can think of would apply to people who are already married in their 20s or to people who eventually want to have children. Unfortunately it’s a scientific fact that it is harder for women to conceive as they get older. Women are more aware of this than men. Many of my friends who are single & in their late 30s early 40s have expressed fear/sadness that they think they missed their chance to become mothers. To be clear, i don’t agree at all with jumping into a relationship just to have a child. But I do think that it would be a reason that someone would want to start a family in their 20s.