How do you decide who gets to procreate and who doesn't? I mean, it's difficult to judge someone's skills at parenting until after they've actually parented.

How do you decide who gets to procreate and who doesn't? I mean, it's difficult to judge someone's skills at parenting until after they've actually parented. Do you let people have one child upto X years old and then go through some objective evaluation with that child to decide if they are allowed to produce more?