Harsh looks at a portrait of a man and says, "His mother is the wife of my father's son. Brothers and sisters I have none." At whose portrait is Harsh looking in this classic blood relation riddle?

Introduction / Context:
This is a classic puzzle with the phrase "Brothers and sisters I have none," which implies that the speaker is an only child. Harsh is describing a man in a portrait in terms of the man's mother and his own family position. The key is to unpack the expression my father's son and then use the information that Harsh has no siblings to find the exact relation between Harsh and the man in the portrait.

Given Data / Assumptions:
• Harsh is looking at a portrait of a man.• He says, "His mother is the wife of my father's son."• He also says, "Brothers and sisters I have none," meaning he is an only child.• My father's son therefore refers only to Harsh himself.

Concept / Approach:
The statement "my father's son" can refer either to the speaker or to one of his brothers. However, since Harsh clearly states that he has no brothers or sisters, the only son of his father is Harsh himself. Therefore, my father's son is Harsh. The woman described as the wife of my father's son is therefore Harsh's wife. If this woman is the mother of the man in the portrait, the man in the portrait must be Harsh's child, specifically his son.

Step-by-Step Solution:
Step 1: From the sentence "Brothers and sisters I have none," conclude that Harsh is the only child of his parents.Step 2: The phrase "my father's son" can only refer to Harsh himself, because there are no other sons.Step 3: Harsh then says, "His mother is the wife of my father's son."Step 4: The wife of my father's son is the wife of Harsh, because Harsh is my father's only son.Step 5: If the woman is the mother of the man in the portrait, and she is Harsh's wife, then the man in the portrait is Harsh's child.Step 6: Since the portrait is of a man, this child is Harsh's son.

Verification / Alternative Check:
As a quick check, imagine Harsh, his wife and their son. Harsh's father is above them in the family tree. My father's son clearly refers to Harsh only. The wife of my father's son is Harsh's wife. Her son is Harsh's son. This matches the puzzle exactly and leaves no room for other interpretations once the only child clue is used.

Why Other Options Are Wrong:
His cousin: Cousins share grandparents but the description uses the speaker's direct spouse and child, not a cousin relationship.His uncle: If Harsh were the uncle, his father's son would have to be Harsh's brother, which contradicts the statement that he has no siblings.His nephew: That would require Harsh to have a sibling with a child, again impossible because Harsh has no brothers or sisters.His father: This reverses the relationship and does not fit the description where the man's mother is the wife of my father's son.

Common Pitfalls:
Many candidates forget to apply the condition that Harsh has no siblings and incorrectly assume that my father's son might refer to someone else. Another trap is to misread the phrase and treat the wife of my father's son as Harsh's mother rather than his wife. Keeping each phrase precise and using the only child condition resolves these confusions.

Final Answer:
Harsh is looking at the portrait of his own son.