Your descendants will overpopulate the whole planet and suffer the horrors of overbreeding if they average more than two children, even if all others in the world stopped having children.
This fact dictates that we must pay attention to how many children we create, how many grandchildren our parents have and how many great grandchildren our grandparents have. If, for example, the community wanted to keep the population numbers stable and you were one of a triplet, then you and your 2 other siblings would not be able to have 2 children each. Your parents should not have more than 4 grandchildren.
Keep in mind that today we must not attempt to keep our numbers stable. They must be headed down.