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But identical twins are very different people despite the same DNA.
by quizbiz 17y ago
But identical twins are very different people despite the same DNA.
- daniel-cussen 17y agoThe identical twins I know are very similar to each other. Just my two cents of a data point.
- tokenadult 17y agoI have nieces who are identical twins (they were tested for monozygosity after being born). But they are not even identical in appearance--I'm decent at telling them apart, and their mom does that very well. Professional geneticists are aware of cases of monozygotic twins being quite discordant in height, IQ, or various other phenotypical characteristics of interest. Some of those cases are reported in detail in the better textbooks on human genetics.
- miked 17y agoBut they are not even identical in appearance--I'm decent at telling them apart, and their mom does that very well. That rather sounds to me like they're very similar in appearance. In any case, it's brains and personality that count the most.
- byrneseyeview 17y agoProfessional geneticists are aware of cases They are also aware of statistics, and confirmation bias, right?
- tokenadult 17y agoHow would confirmation bias tend to run on this issue?
- byrneseyeview 17y agoDepends on how many people grew up watching Sesame Street and listening to NPR, compared to how many people grew up watching... uh... all those mainstream media sources that take the yes-there-is-human-biodiversity side of the human biodiversity debate.
- tokenadult 17y agoI referred to professional geneticists, persons who enter a graduate program of study of genetics and gain a Ph.D. and academic position in that discipline. From above: Professional geneticists are aware of cases of monozygotic twins being quite discordant in height, IQ, or various other phenotypical characteristics of interest. Some of those cases are reported in detail in the better textbooks on human genetics.
- mynameishere 17y agoTwin studies say otherwise. Not sure why you would think this.
- Devilboy 17y agoIdentical twins are amazingly similar - even when they're separated at birth. In fact identical twins reared apart are much more similar than fraternal twins reared together. Check out the wikipedia page on this, they have some nice charts of various traits. http://en.wikipedia.org/wiki/Twin_study http://en.wikipedia.org/wiki/Twin_study
- tokenadult 17y agothey have some nice charts of various traits. I suppose you are referring to Figure 1 http://en.wikipedia.org/wiki/File:Twin-concordances.jpg http://en.wikipedia.org/wiki/File:Twin-concordances.jpg in the Wikipedia article you kindly linked. What that chart shows, of course, is that twins can be quite DISCORDANT in a variety of socially important traits, even though they share a common genome. That should alert us to the fact that more than genes matter in human development. (Pretty nearly everyone agrees that genes matter for something, but the issue is how much expression of genes can be influenced by nongenetic influences on human development.)
- Devilboy 17y agoWell yes, I don't disagree with you there. If you plant two seeds with identical DNA but only give one of them enough water and sunlight then of course they're going to be different heights and weights after a few weeks. But you'll probably not find identical twin brothers where one becomes a NBA pro and the other a jockey.
- tokenadult 17y agoI should have jumped right in while posting my first comment to mention the pair of twins (tested for monozygosity, which no one would believe without testing) whose photograph appears in one edition of the Vogel-Motulsky textbook on human genetics. They are very discordant in height, and one is thin enough to be a horse-racing jockey (but maybe not strong enough for that) while the other is within the height range of professional basketball players, I think. People who read the literature on the subject find amazing examples (which serve as counterexamples to what people in the general public might guess) of all kinds of interesting phenomena of genetics.