Zoology - Principles of Inheritance and Variation Question with Solution | TestHub

In family $A$, if both the parents are homozygous recessive, then both should be diseased and should have $100\%$ diseased progeny. In family $B$, if both parents are homozygous dominant, they would not have got the recessive disease in first place. In family $B$, if both are heterozygous recessive, then also they would not have got the disease, neither $80\%$ of progeny would be diseased.