One of the beautiful things about Jewish culture is that one observes the entire evolution and preservation of human bonds from the family, to the tribe, to the religion, to the state. The familial origin (and fact that Abraham married his half-sister Sarah and later returns to his family for the wife of his son Isaac to begin the tribe – a distinguishing origin from Ishmael who was an offspring from a marriage outside of the family) – initially may have evolved from “family gods” and “family worship” origins, particularly prevalent in Egyptian culture at the time of Jewish religious origin, but also evident in far-Eastern and Indian cultures. This propagates in today’s culture to create very strong foundations for higher social organization. Other forms of government such as kingdoms and dynasties have been established along similar grounds for centuries, although today, in secular societies, government frowns upon partiality in this aspect. Family privilege is anti-democratic. Cultures that were highly incestuous did not tend to survive. Judaism is somewhere in between the two extremes of identity, association, and power being associated with genetics, and identity, association, and power being evenly distributed to everyone.
Before any thoughts of rejection of this from non-Jews are directed here, consider how often in other cultures, families judge whether someone is “good enough” for their daughter or son. Identity, association, and power are generally not democratically allocated when it comes to genetics. So, Judaism balances conserving strong tribal traditions that, depending on how reform one is, must be maintained to be a member of the tribe, with simply considering someone to be better because they are Jewish. I think the vast majority of Jewish parents probably do want their kids to value Judaism to the point where they would want them to marry someone who is Jewish. Loyalty to the tribe is preserved through the family connection. This preserves the culture. Must this desire for cultural preservation be balanced with other ideals?
It’s a question that would probably benefit from some thoughtful analysis and evaluation from fields such as anthropology and sociology.