If fraternal (or dizygotic) twins are more likely to be concordant for a trait than other siblings, can it be concluded that the higher concordance rate is due to the greater degree of genetic relatedness?
a. Yes.
b. Yes, but only if the siblings studied are of the same sex and age.
c. No, because the greater similarity can be attributed to environmental influence.
d. No, because fraternal twins are no more genetically alike than other siblings.
Question 2
Why is it particularly useful to study identical twins who were raised in different environments?
a. Differences in brain function can easily be identified.
b. Concordance rates tend to be higher.
c. It is possible that the genetics of twins who have been separated have changed in ways to explain any differences found.
d. It is possible that high concordance rates between identical twins reared together is due to their being treated more similarly than nonidentical twins.
A family pedigree of a recessive trait.
Red-Green Color Blindness Is a Sex-Linked Trait in Humans
Monozygotic Twins
Stabilizing selection eliminates extreme forms of a trait
Disruptive selection eliminates midrange forms of a trait