Anyone choose to have just one child?

It will probably be one for me but I have mixed emotions about it. As a PP said, when your parents are aging or pass away no one knows that feeling like a sibling. I have so many friends who are dealing with parent health issues as well as raising kids. If they didn't have siblings I don't know how they would keep their sanity. I have 2 sisters and we really are there for each other (and were for our parents too). It's a tough decision. I would hate for my son to be all alone. Interestingly enough, I take a wierd sort of comfort in knowing he's adopted and may have extended family out there who he'll come to know and love.