Identical twins not actually identical, shocking research finds

[anonymaus]

Canadian scientists have discovered that identical twins do not have identical genes, a common assumption by researchers for more than a century, and a development that could have implications into the study of medicine and human behaviour.

"That assumption has been with us since the beginning of time," said Shiva Singh, a molecular geneticist at the University of Western Ontario. "So this finding could be really revolutionary."

It was Singh's research into the relationship between heredity and schizophrenia that led him to his stunning discovery.

Singh had hypothesized that since the risk of developing schizophrenia is much higher if your siblings or your parents have the disease, the risk should be much greater for twins.

Identical, or monozygotic twins develop from a single fertilized egg that has split in two. Based on previous research, their genetic makeup should be identical.

So if the disease was related strictly to genes, the incidence for pairs of identical twins should be 100 per cent. But studies show that the risk of the disease in both twins is only 50 per cent.

Singh figured either the twins do not share exact copies of their genes or the disease involves other random effects.

read more (http://www.ottawacitizen.com/health/Identical+twins+actually+identical+shocking+Canadi an+research+finds/4530997/story.html)

Well then. :eek:

[Psychonaut]

http://turbo.inquisitr.com/wp-content/2009/11/skeptical-hippo-1.jpg

[Stygian Cellarius]

These quotes below I believe to be the important ones.


But after sequencing the DNA of twins and their parents, and looking at one million differences between their genes, Singh concluded that twins are not actually identical.

That's not bad, but I'd like to know how many sets of twins were compared. I don't really care about the parents.


Singh said cells increase or decrease the number of genes that they contain as they replicate.

And it is the variations in which genes and how we express them that make each individual — even identical twins — genetically unique, he said.

This is very important and suggests that due to environmental stimuli a system of cells will alter their performance through a form of selective tandem-repeat gene expression?

I don't know much about genetics, but I thought sequences of repeated genes were considered Junk DNA (although I once speculated that it would be for operational redundancy)? Maybe someone can clear this matter up for me?


And because the process is constant, a pair of twins when they are 60 may have many more differences than when they are three years old, Singh said.


"The genome is very dynamic, not static. What you got from your parents is not what you have in the end," he said. "There is more to the story than that."

Shouldn't this have been discovered via 23andme and other commercial genotyping companies long ago? How could it be missed? Different genes are different genes.

I still find these claims counter-observational. Identical-twins are physically identical. Which suggests that either the variations are ultra-subtle, perhaps even negligible, or Mr. Signh is mistaken.

[Magister Eckhart]

I think this is much more significant to Schizophrenia than it is to twinning. If we can prove that this disease is hereditary, we can prove other psychological disorders are such and begin weeding out schizophrenics, manic depressives, and others through selective sterilization.

[Raskolnikov]

It never made sense to begin with.

[Stygian Cellarius]

It never made sense to begin with.

Pardon me, but...

What in particular didn't make sense about what?

Thanks :)

[Raskolnikov]

Identical twins.

I mean, 'shocking'? Really? No. Not really. Stupid popscience.

[Fortis in Arduis]

I think this is much more significant to Schizophrenia than it is to twinning. If we can prove that this disease is hereditary, we can prove other psychological disorders are such and begin weeding out schizophrenics, manic depressives, and others through selective sterilization.

Or, we could be nice instead and help parents have the best children they can by selecting the best embryos for implantation. :angel

Also: the genes which cause disease when fully expressed might confer benefits or selective advantages when partially expressed, and so removing them from the gene pool could weaken the population as a whole.

[Breedingvariety]

So if the disease was related strictly to genes, the incidence for pairs of identical twins should be 100 per cent. But studies show that the risk of the disease in both twins is only 50 per cent.
Schizophrenia is not only genetic.

Singh figured either the twins do not share exact copies of their genes or the disease involves other random effects.
No way, Sherlock.

[Magister Eckhart]

Or, we could be nice instead and help parents have the best children they can by selecting the best embryos for implantation. :angel

Also: the genes which cause disease when fully expressed might confer benefits or selective advantages when partially expressed, and so removing them from the gene pool could weaken the population as a whole.

Alright so you called my bluff, I suppose - there are really limits I put on the eugenics I'm willing to endorse.

Honestly, though I'm having a hard time figuring out what kind of positive benefits could come from even partially expressed Schizophrenia.

[Fortis in Arduis]

Alright so you called my bluff, I suppose - there are really limits I put on the eugenics I'm willing to endorse.

Honestly, though I'm having a hard time figuring out what kind of positive benefits could come from even partially expressed Schizophrenia.

Eugenics =/= Evil

There will be some benefits from the partially expressed genes which cause widespread anomalies, otherwise they would not survive today.

We know that these disorders have always been with us.