What's a good reason to give your child a sibling? (Besides having someone to play with) :)

It would depend on the kind of parent you are, but personally I am of the belief that when it comes to family and kids, the more the merrier. It'd be hell at first, not only for you and your partner, but for the children as well: there will be a lot of bickering and fights and tuition fees to be paid off, but everything will be worth it.