So, I have another problem with a pedigree. There is an autosomal recessive trait in a family. Father - AA, mother Aa, they have two children one of them is Aa (it is possible) but the other one is aa. And thatīs the problem because she cannot inherit a from her father since he is AA. What could be the possible cause of that?? How can it be explained?? (the woman did not sleep with the postman ;P)