I do not understand much of the rhetoric of a “duty” to follow “natural affections” in terms of ethnicity or kinship.

The Bible commands things regarding parents and children regardless of blood or adoption. The Pauline epistles list obligations between husband and wives, parents and children, and slaves and masters. It makes no obligation on you regarding spending time with a cousin as opposed to a best friend you met in college.

As a matter of wisdom, the Bible indicates you should prioritize your location over your extended family. “Do not forsake your friend and your father’s friend, and do not go to your brother’s house in the day of your calamity. Better is a neighbor who is near than a brother who is far away” (Proverbs 27:10).

Also relevant:

“And if the household is too small for a lamb, then he and his nearest neighbor shall take according to the number of persons; according to what each can eat you shall make your count for the lamb” (Exodus 12:4).

Note the directive is for closest spatial proximity, not nearest kin. Tribal Israel had some wider obligations, but the tribal stage of the Kingdom was later replaced by other structures around the nuclear family. By Biblical design, families never expanded longer than a generation. The children grow up to start their own families (Genesis 2:24). And even with the family-line oriented law of levirate marriage, location was a qualification for there to be an obligation (“If brothers dwell together…” [Deuteronomy 25:5]).

The language of “natural affections” seems dishonest to me. It seems to pose as merely descriptive while smuggling in prescription. It is Lady Catherine de Burgh insisting that Elizabeth has made Darcy “forget what he owes to himself and to all his family,” and preaching to her: “If you were sensible of your own good, you would not wish to quit the sphere in which you have been brought up.”

We all know that humans can find the exotic and strange alluring and the familiar boring. Within the commands of God there is nothing wrong with a preference for the exotic over the familiar. It is completely beyond anyone’s authority to condemn it. We shouldn’t be trying to create obligations upon such abstract characteristics. “I am very dark, but lovely, O daughters of Jerusalem… Do not gaze at me because I am dark, because the sun has looked upon me” (Canticles 1:5,6).

The fact that the Bible outlaws sibling marriage is a warning against building a society on attraction only to the familiar.

In Israel, men were tied to the land while women were ordinarily free to marry throughout Israel. This would mean a man had the right to prefer someone different over those he grew up with, and vice versa.

Is this simple aspect of human nature being portrayed as perverse? And now that our serfdom to the Land has ended (Galatians 3:23-4:7), why would we now want to try to reanimate that tribalism?

There are bad aspects to the contempt bred by familiarity, of course. “For Jesus himself had testified that a prophet has no honor in his own hometown” (John 4:44; also Matthew 13:57; Mark 6:4; Luke 4:24). The “generation gap” probably exists mainly because of that aspect of human nature and is commonly practiced both towards one’s parents and towards one’s children, once they have the temerity to become adults.

Is that always bad?

Some children apostatize and some parents age horribly. But some are “ransomed from the futile ways inherited from your forefathers” (1 Peter 1:18). No one in America can possibly claim to appreciate American culture and yet condemn those who abandon their native lands for a possible new world.

Christians have the Bible in the Church. They do not need help from these vague and falsely universalized claims about “natural affections.”