I have one child, I had her the day before my 30th birthday, I am now 40. I had wanted to have more then one child but I didn't want to do it on my own and I have not been married to have one with a spouse. Even if I were to get married now, I can't imagine having another child 10 years later.
I can't imagine having a child after that long. How old must these people be? If their daughter is 31 they must be in their 50s which would mean they must have had to go through artificial insemination and egg donation.
I think sometimes people do things to feel like they are still young. Some buy convertibles, some men grow their hair long, some have children. I think people should just let it go and grow old gracefully.