Why not? They are capable, taking such a decision at that age means that they have thought about it in depth, probably have the financial circumstances to care well for the child, they have as much love as anyone else and a hell of a lot of experience. Fifty is not old - wait until you are close and see how you feel - and what children need is love and stability. As for the possibility that the parent may die when the child is in early adulthood - do we ban smokers from having children?