Table of Consanguinity

[AloneTooLong]

My Dad's parents shared the same great-grandmother and no one was concerned about them getting married; my Father was astounded when my sister-inlaw told Dad it would be 'incest' had I accepted the marriage proposal of Dad's younger brother!

 

[Bramblethorn]

I think there are several things at work here.

One is the utility of bright-line rules. Bright-line rules can be underinclusive or overinclusive and result in injustices in specific cases, but they're simple and easy to administer, and I think they resonate with people. "No incest" is a simpler rule than "no incest between males and females, but male-male incest is OK because no genetic deformities will result." It's at least possible that the adoption of the bright-line rule, because it's clearer, creates a net social benefit because of its clarity. I'm speculating, of course.

[snip etc.]

This would be a valid argument for keeping laws the way they are, but I'm less convinced by it as an explanation for why the laws we have happened to end up this way. I suspect part of it is that although these particular prohibitions were instituted for historical-cultural reasons which are no longer as strong as they once were, dropping them would require fairly specific changes and nobody has much motive to spend political capital on legalising brotherfucking. Even on Literotica, gay incest doesn't have a lot of champions.

 

[SimonDoom]

[snip etc.]

This would be a valid argument for keeping laws the way they are, but I'm less convinced by it as an explanation for why the laws we have happened to end up this way. I suspect part of it is that although these particular prohibitions were instituted for historical-cultural reasons which are no longer as strong as they once were, dropping them would require fairly specific changes and nobody has much motive to spend political capital on legalising brotherfucking. Even on Literotica, gay incest doesn't have a lot of champions.

Absence of political capital is probably a big explanation why things don't change faster. It took a long time in this country to get rid of "sodomy" laws, even though most people probably thought it was wrong for the law to intrude upon what people did in their bedrooms, just because there was no political gain to be had from pressing for decriminalization. I imagine that's even more true of incest. I can't imagine there ever being a big lobby for legalization. But it still leaves open the question of how the law got this way in the first place.

 

[Britva415]

My Dad's parents shared the same great-grandmother and no one was concerned about them getting married

So, second cousins

 

[jehoram]

And if you diagram the consanguinity of some of the European royal families, you get something that looks like a diagrammed football play, with arrows pointing everywhere.

 

[Bramblethorn]

So, second cousins

If they also shared a great-grandfather; otherwise, second half-cousins, I guess.

 

[gunhilltrain]

I came across this illustration in some old files and thought others might benefit from its depiction of familial relationshipdView attachment 2454809

Thanks, I wouldn't know most of this. Probably in most of the world until the 19th Century, when family was so important, people would have much of this in their memory. I'd guess that one's "clan" was extremely important for centuries.

In the modern West (and East Asia), especially the United States, families have gotten smaller because of various factors, including declining birth and marriage rates. Also, existing families fly apart because of divorce and increased mobility. In 1800, few people went more than fifty miles from home unless it was part of a war. It was just difficult to move around. Boston to New York took around a week by horse or a horse-drawn vehicle.