Friday, March 27, 2015

quotes from Human Behavioral Genetics

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This week in Human Behavioral Genetics (taught by Matt McGue) we are learning about twin studies.  We have been told that the evidence is clear and convincing that monozygotic ("identical" ) twins are more alike, as adults, than are dizygotic ("fraternal") twins.  Regardless of whether the twins were raised together by the same parents, or separately by different sets of parents.

This is true for physical characteristics, like height and weight, and it is also true for personality characteristics like how likely twins are to both be religious, or both be politically liberal or conservative.  Pretty much across the spectrum of human traits, monozygotic twins are more like each other than dizygotic twins are like each other.  Regardless of who raises them.

The quotes below are from "Sources of Human Psychological Differences:  The Minnesota Study of Twins Reared Apart" -- Thomas J. Bouchard, Jr.,  David T. Lykken, Matthew McGue, Nancy L. Segal, Auke Tellegen.

"Psychologists have been surprised by the evidence that being reared by the same parents in the same physical environment does not make siblings more alike as adults than they would have been if reared separately in adoptive homes."

"The genes sing a prehistoric song that today should sometimes be resisted but which it would be foolish to ignore."



Interestingly, IQ (only about 70% accounted for by genetics) is one of the traits that is most influenced by "nurture"........  We're going to have a whole week on IQ, later in the course.
 

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