Human family is not a charity or expensive hobby or a financial punishment for poor contraceptive techniques. Human family, like a family of any living beings (swans, lions, elephants) is a social procreation team. The objective purpose of a human family is extending the family line of its ancestors. People, who share the team objective, are a part of their family teams. People, who decline to contribute into the team objective (e.g. ChildFree by Choice), are not part of their family teams.