I live in Utah, I am LDS (or, Mormon as it is sometimes called), and pretty much everyone around me is. We have our beliefs, and are not as crazy as some people think we are. We believe in Jesus Christ, he is our savior. We believe that his true church was lost from the earth and that it was restored through a man named Joseph Smith. We continue to have a prophet to this day who leads and guides the church by revelation from God.
We do have some weird habits, things that come out of our culture more than our religious beliefs. One of which is children. We are not polygamists, but we still like large families. To prove this is not a rule and you will not be shunned, I am an only child, so no big family there. I find it funny in shows when people think that four kids are a lot of kids to have. Four is average, six is common, 10 is big (yes, I've known people with 10 kids and they get along just fine.)
So when in one of my classes when a non-LDS girl suggested one way to be green was to not have any kids, half of the class laughed. The half that didn't, not LDS. You see, half of those guys, are about 25, and have at least one kid already and plan on much more. She then tried to get us to see, that maybe only two kids was the way to go.
I see her point, there isn't a lot of the earth to go around, so if you are just replacing yourself, one for you, one for your spouse, then it isn't creating that much of an impact. People have needs and if you don't create another person, than those needs are gone. It makes sense, but how realistic is it? In some overcrowded parts of the world people are limited in the amount of children they can have, and even end up killing the girls so they can have guys.
I don't plan on doing this, when I finally get around to being married and have kids (this is also a religion thing, marriage before sex.) In fact in all my daydreaming houses I've always planned for six kids. Whether I have them or not? Well, I'm going to let my husband help decide that, not mother earth.