The concept of inbreeding dangers is well known in biology – the more often the family tree intertwines, the greater the dangers of congenital birth defects – those defects that are in the genes.
Most of us carry some defective genes – we might only be aware of the dominant ones. Recessive genes, as they only represent when the other parent also passes one on, may ‘hide’ for generations.
Those recessive traits will naturally turn up more often when both parents share common ancestors. Such was a problem with many of the ruling families of Europe in the mid- to late-20th century. As the number of royal families dwindled, their heirs had fewer choices for partners.
Marriage outside of the extended family? This led to less stability in the power elite, who had less of a stake in supporting the monarchies.
The same dynamic comes into play with some cultures that limit their breeding pool to extended family members. In some parts of the world (most notably with Muslim cultures, Arabic or not), marriage with even relatively close family members is encouraged – cousins, uncles, etc.
What has this led to?
I don’t see this changing much soon. The practice, as mentioned above, also increase group/familial cohesion, and keeps the money (bride-price) in the family. Other than forcing genetic testing on prospective spouses before issuing a visa (unlikely in the current climate of Western Countries, and likely to lead to cheating on the tests), I don’t see this changing in the near future.
My suggestion? A complete ban on immigration for a generation or two. It’s the solution that finally began to get the Sicilians to marry outside of the gene pool.
By 1930, more than two-thirds of immigrants had applied for citizenship and almost all reported they could speak some English. A third of first-generation immigrants who arrived unmarried and more than half of second-generation immigrants wed spouses from outside their cultural group.
The Immigration Act of 1924 virtually shut down Italian immigration (among other groups), and led to their assimilation through intermarriage to other groups.
If a person chooses to marry someone from “the Old Country”?
Fine. You can either live apart until such time as that person qualifies for NON-family visa status, or – my preference – go to that country and live there – permanently. No, your citizen status should NOT transfer to your children, as you will be subject to the laws of your spouse’s country. Naturally, those serving in the US military are exempt.
Add on a provision that no person who has been naturalized may themselves sponsor another immigrant, and you’ll go a long way towards reducing chain migration.
Is this a sign that I’m anti-Non-Whites?
In America, at this time, we have a lot of indigenous citizens who, as far as I am concerned, get first call on any charitable or government assistance to reach economic independence. Americans First.