The family is responsible for producing new members
Family heritages can be traced for generations and connect to a broader name or identity. Families have a responsibility to continue their family name through their posterity.
Producing offspring is a fundamental necessity for life. A species must be able to reproduce in order to survive. Moreover, a species must reproduce with genetic variation to most successfully survive. Human genetics are finite. The only way to pass down genetics, characteristics, phenotypes, or other hereditary traits is to have children. Families have a duty to continue their family name by producing offspring. Giving birth to children brings value to the world. Valuable people (having special genetic features) produce offspring with similar valuable genetic traits. In addition, the creation of life itself is the most valuable characteristic of life. One’s progeny “carries its share in society” for future generations to benefit. Families have a duty to produce offspring. Procreation is not only a defining characteristic of a family but of life in general.
Families can still make an impact on society without leaving offspring. Some families may not be able to have children, have financial limitations, or may choose to not have children. For example, Mother Teresa and Sir Isaac Newton both bettered humanity with their respective contributions, all without starting a family or leaving offspring. They still left a valuable impact—albeit not children—on society for generations to come.  In addition, humans can procreate without being a part of a family. People can choose to have a child in traditional means, yet not start a family. Similarly, mothers can give birth to a child with other means (such as a sperm bank) but still choose to not form a family.