Razib Khan One-stop-shopping for all of my content

March 24, 2011

Twins: Brazil edition

Filed under: Brazil Twins,Genetics,Genomics,Josef Mengele,Twins — Razib Khan @ 7:27 pm

A few years ago a story came out about a town populated by Germans in Brazil which exhibited a tendency toward twinning. The combination of Germans, Brazil, and twins, naturally meant that Josef Mengele came into the picture. A more prosaic explanation for the twinning, favored by locals, was that it was something environmental, like their water. The oddity warranted coverage by National Geographic, and you can imagine what the British press did with the story. At first I thought I saw references to elevated frequencies of identical (monozygotic) twins, which would have have been strange indeed. Twinning varies across populations and families, but that variance tends to be of the fraternal (dizygotic) variety. Some of this is heritable, but some of it is clearly due to environment. Specifically, nutritional inputs that increase levels of insulin-like growth factor, which is found in milk and meat (I suspect this explains the higher twinning rate in Northern Europe vis-a-vis Southern Europe). This doesn’t even go into other factors brought on by modernity, such as delayed childbearing and fertility technology.

But in any case, it turned out that the Brazilian twins were ...

March 13, 2011

Think twins!

Filed under: Bioethics,Genetics,Genomics,Identical Twins,Twins — Razib Khan @ 8:40 pm

In the comments below, John Howard asks in relation to me releasing my genotype into the public domain: “I’m curious if this means you give permission to be cloned, or for someone to reproduce with you, by making gametes from your genome. Do you think other people have the right to do that?” I’ll be honest that I laughed when I first saw this comment. My genome is not magical. If someone wants to make more of me (and I can see why they’d want to do that), I probably wouldn’t mind. My siblings are versions of me diluted by a factor of 1/2, if you want to think in terms of blending analogies. But the biggest issue is this: identical twins already share very concordant genomes, and no one would presume that one twin should have a right to a say in the use of the genome of the other twin. Then again, John Howard runs a website EggsAndSperm.org, “Dedicated to stopping genetic engineering of human beings, and preserving individual conception rights for all people. All people should be created equal, by the union of a woman ...

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