PSYC 2P25 Lecture Notes - Lecture 6: Trait Theory, Heritability, Epistasis
9 Nov 2012
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Researchers want to find the heritability (h2) of a trait the proportion of the trait variation that is due to heritable (genetic) variation in a give population. To find the heritability of a personality trait, we need to know whether (genetic) relatives have similar trait levels beyond any similarity due to their common environments. 1) study many set of identical (monozygotic; mz) twins raised apart: mz twins share 100% of genes. 2) study many sets of fraternal (dizygotic; dz) twins (or even non-twin siblings) raised apart: dz twins share 50% of genes (same as for non-twin siblings). E. g. r= 30 -> h2 = 2(. 30) = . 60. In example given above, the r for mz twins together r(. 60) was exactly twice as big as the r [add from notes] First, it"s possible that the r for mz twins together could be more than twice as big as the r for dz twins together.
