All it needs is for each person to have the right to have, say 2 children and strictly enforce that by agreeing to registered sterilisation after that has been reached. DNA will keep it honest. With the level of infertility and early deaths in many countries it could even be 3 in some countries? Surely everyone would be happy being able to have 2 or 3 kids? Whatever is needed to arrest the population growth and see it slowly begin to fall.
