Pointing to a photograph, Anjali said, "He is the son of the only son of my…

Blood-relation puzzles describe a person through a chain of relations built on a fixed reference person. To decode the chain, resolve it one link at a time starting from the reference point (here, "my grandfather"), tracking two things at each link: whether the description picks out a unique person (one-of-many vs. the only one), and the stated gender — both are needed to name the final relation.

1. "The only son of my grandfather" is a uniquely identified person: since the grandfather has just one son, that son must be Anjali's father.

2. The photograph shows "the son of" this person — i.e., a son of Anjali's father — one generation below the grandfather's son, which places him in the same generation as Anjali.

3. The pronoun "he" fixes the photographed person's gender as male.

4. A male in Anjali's own generation, sharing the same father, is her brother.

Reworking the chain top-down gives the same result: grandfather → his only son (a single, fixed person) → that person's son (the photograph) — two steps down from the grandfather and one step down from the referenced parent, landing exactly at Anjali's own generation.

• Uncle would require the photographed man himself to be the grandfather's only son — one generation above where the statement actually places him.

• Son would require Anjali herself to be the parent in the chain, but the chain never passes through Anjali.

• Data is inadequate is ruled out because the statement fully pins down a single individual ("only son") and fixes gender ("he") — nothing is left open.

Hence, the man in the photograph is Anjali's brother.