I have two siblings. One with children; one without. Our mother said, "choose what's best and right for you." Their in-laws said, "have kids, have kids, have kids" (almost from the moment the engagement ring was placed on their fingers). The one who has children, feels pressure to keep pro-creating. The one who doesn't have children, and is more than pushing the boundaries to even safely consider it and is very firm against it as always, still hears "have kids" from her in-laws.
My mother in law was a little off balance and could never remember whether or not I had kids, so never really bugged me.
