10. The trait shown in the above pedigree is
(1) X-linked recessive trait
(2) Autosomal recessive trait
(3) Y-linked trait
(4) X-linked dominant trait

The trait in the given pedigree is an autosomal recessive trait, so the correct answer is option (2) autosomal recessive trait.​

Understanding the pedigree

In the third generation, both parents are unaffected, yet all three children (two males and one female) are affected, which is the classic hallmark of an autosomal recessive inheritance where unaffected heterozygous carriers produce affected offspring. In autosomal recessive traits, males and females are affected in roughly equal proportion, as seen here, and the trait typically appears to “skip” a generation because carrier parents are phenotypically normal.​

Why option (1) X‑linked recessive is wrong

For an X‑linked recessive trait, affected males usually inherit the mutant allele from carrier or affected mothers, and affected males are far more common than affected females. In this pedigree an unaffected female (third generation) has an affected son, which is not possible for a true X‑linked recessive trait because a normal (non‑carrier) mother cannot produce an affected son with an unaffected father.​

Why option (3) Y‑linked trait is wrong

Y‑linked traits are seen only in males and are transmitted strictly from affected fathers to all their sons without skipping generations. In the given pedigree, both males and females are affected and there is no strict father‑to‑all‑sons pattern, so Y‑linkage is clearly excluded.​

Why option (4) X‑linked dominant is wrong

X‑linked dominant traits usually show more affected females than males and show no male‑to‑male transmission; an affected father must pass the trait to all his daughters and to none of his sons. In this pedigree, an unaffected couple has all affected children, which cannot be explained by an X‑linked dominant allele because at least one parent would need to be affected for a dominant trait to appear.​

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This article explains a CSIR NET pedigree analysis problem where students must determine what kind of inheritance pattern the trait shown in the above pedigree follows. By applying standard rules of pedigree interpretation, it is shown step by step that the correct answer is an autosomal recessive trait, and that X‑linked recessive, Y‑linked, and X‑linked dominant options are incompatible with the given family data.