Would u carry your son/daughters child?

I would consider it for my kids, but I think I'll be too old by the time they have kids. My friend half-jokingly asked me if I would be a surrogate for her if she can't get pregnant. I told her that we would have to go through tons of counseling, I bond immediately when pregnant with the baby, and she would be stuck with me in her life forever no matter what. She then said that she has her mom, her sister, and a friend that have also offered. I think it would be the hardest thing in the world to do.