Not being a parent is selfish

I feel strongly that those who are able and married should have children. Of course God feels the same way, as He gave the commandment to multiply and replenish the earth. I guess the point I'm trying to make is that there are many people in the world that don't want to have children for various selfish reasons. I want to pursue my career, I want some time to ourselves, we want to travel, children are to burdensome, I'm scared that we will get a divorce are among some of the reasons people give for not deciding to have kids. The thing that gets me is that people seem to forget the fact that everyone was once a kid. Someone raised you, changed your diapers, fed you, put up with your fits and took care of you. Why should you not be willing to do the same for someone else. Our textbook pointed out that many families are having fewer and fewer children than in the past. This means that family sizes are getting smaller and there are more families with just one kid. In class we discussed some of the negative and selfish consequences that being an only child poses to that child. Without brothers and sisters to learn from it is harder to learn some of the essential things like sharing.