Question

Researchers studying genetic determination of childhood asthma noted 65% concordance for monozygotic twin pairs in which at least one twin has asthma and 37% concordance for dizygotic twin pairs in which at least one twin has asthma.
a. Explain the meaning of 65% concordance for asthma in monozygotic twins.
b. Interpret the difference in concordance for asthma between monozygotic and dizygotic twins.
c. If genes do influence childhood asthma, how is that 35% of monozygotic twin pairs are discordant for asthma?

Answer 1

(A)--Sixty-five percent concordance indicates that in 65% of monozygotic twin
pairs in which one twin has asthma, the other twin will also have asthma.

(B)--The significantly higher concordance in monozygotic twins compared to
dizygotic twins indicates that genes play a major role in contributing to
childhood asthma. The difference can be attributed to the fact that
monozygotic twins share 100% of their genes, whereas dizygotic twins only
share 50% on average...

(C)---ENVIRONMENT PLAYS PART .Given
that the monozygotic twins are genetically identical, their different
phenotypes must be due to differences in their developmental
environments.