Below is a pedigree of a fairly common human hereditary trai

Below is a pedigree of a fairly common human hereditary trait in which the boxes represent males and the circles represent females. Shading symbolizes the abnormal phenotype. Given that one gene pair is involved: Is the inheritance pattern X-linked or autosomal, recessive or dominant? Justify your answer.

Solution

Answer

It is not X linked. To produce affected female, the male parent must have the trait. So it is autosomal inherited.

It is not dominant. Because, without expression of the trait in the either parents, it would not be exhibited in their progeny.

Finally, I have come to the conclusion that the pedigree is showing autosomal recessive inheritance