Would you chose to block your childs' fertility until they were 18?
Let's say a medicine was invented that would safely block both male and female fertility until they were 18 without any side effects. Would you give the med to your child? How about if it was until they were 16? 21? When? Why? Why not?
Let's assume for this discussion that this drug has been proven over many generations to be absolutely safe and cause no long term infertility.