Tuesday, June 21, 2011

Incest and DNA

My son in Nome, referencing another grim situation that has come across his screen, said that the joke about the villages is that a virgin is defined as a girl who can run faster than her father. “The Villages” means almost entirely Native populations, Yupik and Inuit. I had heard the sad joke about other places many times – first, I think, about the peninsula counties of Maryland in the 18th C, though the reference was to being able to run faster than one’s uncle. The accusation has been made about Appalachian areas as long as I can remember (though those often took the form of cousin-marriage jokes), and I am starting to hear that incest is distressingly common in some African groups recently coming to America. There were towns and village sections of NH that were rumored to be incest-ridden – being familiar with the dark side of social histories in this state over the last 35 years, I can confirm that some of the rumors, at least, are true. (I have no sense there is any ethnic difference, BTW.) I had only heard of brother-sister incest in professional settings, never in news stories or general discussion, but that is being acknowledged recently. We have long known that step-relatives are far more risk to children than blood relatives, and the data are bearing this out.

We have lived in a swirl of rumor with little data all these years, and the excesses of recovered or implanted memory have added to the confusion. We have speculated whether certain cultures are more prone to incest, but our knowledge has been so limited that this has been irresponsible. I have suspicions on that score, but disbelieve them myself. We have identified some common themes that seem to be holding up – that older siblings are more likely to perpetrate on brothers and sisters when no father is present; that father-daughter incest is more common when the mother is unavailable, depressed, or loses to her daughter in some competition for power in the family; we have wondered whether particular dislocations of culture, such as expulsion or refugee status, create an increase because of the thoroughness of family breakdown, though that is only theory.

That drug and especially alcohol abuse co-occur is one of the strands of information we actually do know with confidence at present.

We are about to start knowing the answers to these questions. And some among us are going to be harmed by it and fight to insist it isn’t true. If whites of certain groups or subcultures show up badly, expect an increasing in them pointing out terrible things that black or Hispanic people do – unless of course there are subgroups of blacks or hispanics exposed under the same light. This will be knowledge we don’t want to have, but we will have it. I don’t know whether we’ll be able to disguise the truths on this one.

One note on how cultures that are either prone to such breakdowns or have such breakdown thrust upon them have been able to survive darwinian selection, given that more children with disabilities would seem to decrease group survival: think of it as natural selection in high gear, if tribes leave the weak behind. There will be little or no greater chance of exceptionally good genes for survival, but the bad genes will be expressed rather than being carried in secret, and weak lines culled. Rather chilling, even if one is considering our ancestors of 100,000 years ago. We may all have benefited from it.


jaed said...

It seems to me that you're mingling at least two things here:

1 Incest: Marriage and childbearing between relatives closer than are allowed to marry in our tradition (possibly socially sanctioned, possibly not)

2 Rape of children who have a legal or blood relationship to the rapist

Very different situations, it seems to me, on many levels. The jokes are about #2; the supposed genetic problems are related to #1 (and color me skeptical about that statement that "Children born to first-degree relatives have a developmental disability about half the time"). The testing will detect situation #1 but not situation #2 - and stepfathers sexually abusing their teenage stepdaughters seems to be much more likely when there is no blood relationship.

Anyway, disentangling these two threads may be helpful in thinking about this.

(Also, as a side note, I hope this test accurately shows what it claims to show. I don't know enough about the field to characterize the word "evidence" in "large blocks of identical DNA are evidence the child's parentage involved first-degree relatives", but DNA testing generally gives us probabilities, not absolutes. It's not hard to imagine multiple lives blown completely apart by well-meaning people working on possibilities-turned-into-absolutes by misunderstanding the technical realities.)

Gringo said...

The testing is done to find the disorder's genetic basis, typically involving mutations, deletions or duplications. But large blocks of identical DNA are evidence the child's parentage involved first-degree relatives.

Children born to first-degree relatives have a developmental disability about half the time, said Beaudet.

Which shows that the folk taboo against incest has been found to have scientific support: it is bad for optimizing species survival. So much for "irrational folkways."
"Irrational folkways" have survived a long time because they have, through trial and error of the centuries, been proven to work. The taboo against incest was probably based in part on the observation that the offspring of such births had a greater tendency towards birth defects.

Those who would willy-nilly overthrow such "irrational folkways" such as marriage being between people of the opposite sex would do well to ponder this.

But they won't, as they are certain they know what "progress" is. "Progress" is anything that is different from what one's predecessors did.

Texan99 said...

I've had three fairly close acquaintances who were the victims of incest: all white, economically comfortable families of above-average education. The perpetrators were one stepfather, one father, and one older brother. The victims: one male, two females. These weren't vague or disputed memories but sustained abuse.

This strikes me as a lot. None of the families ever really confronted what had happened. The stepfather will deny it happened until the day he dies; his stepson died long ago of AIDS. The friend whose brother had a habit of assaulting her worked up the courage at last to tell her mother, who replied, "Oh, I'm so sorry you waited to tell me. We could have done something more to help your brother."

At least no pregnancies resulted.