20.1 If you get the Sunday supplement magazine “Parade” with your paper, you may have seen last week’s “Ask Marilyn” column…if not, here it is…and I might mention that if you see facial hair drawn on Aunty Ask’s picture, your computer has definitely been hacked, because I would never do such a thing, not in a million years…
20.2 On the other hand, how time flies when you’re having fun. Should she have attempted to explain something as complex as Pedigree Collapse in the column space allotted? No. Does the woman who’s said to have the world’s highest IQ have to get cutesy with worlds like “gazillion”? Again, no. Should she have drawn a chart instead? No and double no, as you can see when I tried it, Chart 67. [Helpful household hint: if you click on a chart, you can see it bigger…print it out, even.]
20.3 My problem with Aunty Ask, apart from when she gets things completely wrong, is that she doesn’t do a very good job explaining things. In this case, she is accurate, altho by its nature the topic is blindingly complicated, as Chart 67 demonstrates. And she might have further explained that “16 fourth-generation ancestral positions, filled by only the original eight people” applies to just one set of E generation siblings. In the normal course of events, all 4 sets would have 16 distinct individuals as 2C grandparents, for a total of 64 different people, whereas again here there are only 8. So this indeed is a valid, if unrealistically extreme, example of Pedigree Collapse…even the royal houses of Europe didn’t get quite this bad.
20.4 And since she doesn’t mention it, you might wonder if we’re dealing with interbreeding here? (That’s my latest euphemism for incest/inbreeding) Well, each of the 8 members of the B generation is a 1st cousin to 4 other B’s…and of the 4 B marriages, 2 are between 1st cousins. How does this impact the C generation? Just looking at the 4 males…2 are both 1C and double 2C to each of 2 others, and quadruple 2C to the 3rd. The other 2 are both 1C and double 2C to each of 2 others, double 2C to the 3rd, and double 2C to himself…since 2 of the C’s have parents who are 1C’s. That’s that’s just the C males! You’ve got the C females, plus the D’s and the E’s…perhaps someday I’ll write it all out…but today wasn’t the day…
20.5 Funny thing is, she didn’t have to do it with cousin marriages…for example, Ben/Bess, Bryce/Brooke, Blake/Bette, and Brad/Bea would all be non-cousin matches. In Chart 68, the 4 sibling pairs of the A generation are colored teal, yellow, gray and pink…thus 2 colors are passed on to each member of the B generation, making it easy to trace 1st cousins. By simply trading Ben and Blake’s places, you get 4 marriages, each with 4 different colors, hence no cousin marriages. She had Ben/Bette who are “pink” cousins, and Blake/Bess who are “yellow” cousins.
20.6 Still, this doesn’t make B generation relationships any less complicated. The 2 C’s who were both 1C and double 2C to each of 2 others, double 2C to a 3rd, and double 2C to themselves remain unchanged. But the 2 who were both 1C and double 2C to each of 2 others, and quadruple 2C to the 3rd….are now double 1C to one, and quadruple 2C to each of the other 2. And if you think that’s an improvement, you’re a better man than I, sez me.
20.7 And not for nothing, but I don’t know where she gets that world population of 2.5 million for the “first calendar year.” Experts put the world population in 1 AD at between 150 and 300 million, and even in 10,000 BC, it was between 1 and 10 million. And your direct ancestors in 1 AD…2 to the 80th power for 25-year generations…would be a little over 1 septillion, that’s 1 followed by 24 zeros…a trillion trillions, considerably less than a gazillion, which is equal to a jillion zillions.
20.8 In getting to the answer, we’ll correct a couple of errors. Your situation is illustrated in Chart 69. “…our children share the same great grandparents as each other.” Not really, no. As you can see, they share 4 great grandparents, the same 4 individuals that you and your double 1st cousin share as grandparents. But each has 4 other great grandparents they don’t share, so while you and your double cousins share all your grandparents, your children only share half their great grandparents.
20.9 “…they are closer than second cousins or first cousins once removed.” The CR for 2nd cousins is 1/32, and for double 2nd cousins, which is what your sons are, it’s 1/16…and that’s indeed closer than 2nd cousins…but only as close as, not closer to, 1st cousins once removed, which is half of 1/8 = 1/16 also.
20.10 So tell your children they are double 2nd cousins, which is to say, 2nd cousins thru 2 different sets of great grandparents…”single” 2nd cousins would be the descendants of just one pair of great grandparents. Your guess that they might be called “second double cousins” is wrong because “double cousins” is an informal term for having 2 different kinds of cousin relationships…what is called “irregular 2nd cousins.” It is used instead of a complicated explanation of the 2 different relationships, like “half 1st cousins on one side, 2nd cousins once removed on the other side.” If, as in our case, both cousin relationships are 2nd, then the double is not irregular, and the correct term would be “double 2nd cousins.”
20.11 “Double cousins once removed” is wrong for the same reason, and also for a second reason: your 2 sons are of the same generation, not removed or separated by 1 generation.
20.12 You’re right that you are double [1st] cousins…you’re also right on the CR…25% or 1/4 versus 12.5% or 1/8. But where you get the notion that double cousins implies incest, I don’t know. There is certainly none your case, Chart 70…no blood relatives have procreated with each other, that I can see.
20.13 Now the opposite is true…interbreeding between relatives of the same generation does create some sort of double cousin relationship. For example, in Chart 71, if Abner and Zeke’s parents are siblings, then Abner and Zeke are, besides brothers, also double 1st cousins…this is because Abner’s father is the brother of Zeke’s mother…and Abner’s mother is the sister of Zeke’s father. That we’re talking about 2 people here instead of 4 doesn’t change that double 1st ousin relationship.
20.14 And double cousinship implies a reduced variety in the individuals’ genetic heritage…shuffling with half a deck, as it were. The closer the relationship, the fewer genes you have to pick from…and the greater the risk you’ll get a bad one. For Abner and Zeke, it’s 1/2 + 1/4 = 3/4…half again as close as normal siblings.
20.15 Getting back to Chart 70, the worst that’s going on is in-laws marrying in-laws…cultural and religious views of this practice vary across the board, from forbidden to required, as in having to marry your dead brother’s widow in Bibical times. But in-laws aren’t generally blood relatives. So to answer your question as to what you could call yourselves, you have a problem…
20.16 Because saying “non-incestuous D1C” or “non-inbred D1C” or “D1C but not siblings” or even “D1C with different parents” might imply to the listener that you think he has as dirty a mind as you apparently do. On the other hand, it’s quite possible they won’t know what the heck you’re talking about….while people generally accept the notion that, for example, the children of siblings are “too closely related,” it’s unlikely they understand what that relationship technically is…i.e. siblings and double 1st cousins. So they may wonder why you’re bringing it up…is there fire where there’s smoke?
20.17 Another way you can say it is “parallel double 1st cousins,” since “parallel” applies to brothers of your bather and sisters of your mother….”cross” means brothers of your mother and sisters of father. These are anthropologists’ terms. But it’s most likely that people who understand “double cousins” do so because they have them in their family, and they don’t associate it with interbreeding, so don’t you either…well, try anyway…and we’ll catch you here again next week.
This public service ad also appeared in last Sunday’s paper…looks like the old tinker-toys are catching on, nez pah?
Copyright © 2011 Mark John Astolfi, All Rights Reserved