In a twin study of 1000 MZ pairs, 625 pairs were found to have both twins with the same form of a given trait. In a study of 1000 DZ twins, 426 pairs were found to have both twins with the same form of that trait.
a. What parameter can be calculated from this data?
b. Calculate it for MZ twins and DZ twins, showing your calculations.
c. What does this parameter tell us about this trait?