Blood Relations
Blood relation questions disguise a simple family tree behind a wordy riddle, and the fastest route to the answer is converting the sentence into a small diagram before naming the relation.
10 questions · 5 minutes · instant scoring
What this topic actually tests
A blood relations question describes family connections either through a chain of short factual sentences ('A is B's brother, C is B's mother') or through an indirect riddle spoken by one person about another ('Pointing to a photograph, a man said, She is the daughter of my grandfather's only son'). The reliable method is to convert every sentence into a small family-tree sketch using generation levels - grandparents on top, parents in the middle, the speaker's generation below that - and connect people with simple lines rather than trying to hold the relationships in your head. For riddles, resolve the innermost phrase first: 'my grandfather's only son' should be evaluated before deciding who 'she' is, since it usually collapses to a single already-known person, most often the speaker or the speaker's parent, once the word 'only' fixes the family size. Pay close attention to gender-specific relation words - son versus daughter, brother versus sister, father-in-law versus husband - since CLAT deliberately uses precise terms to test whether you tracked gender through the chain accurately. Some questions instead define a private symbolic code, such as 'A + B' meaning A is the mother of B, and 'A × B' meaning A is the wife of B; here you must apply each symbol strictly left to right along the chain, since reversing the order of who is whose relative changes the answer entirely. Worked example: 'Pointing to a boy, a girl says, He is the son of my father's only daughter.' Since the girl herself is her father's only daughter, 'my father's only daughter' resolves to the girl herself, so the boy is simply her own son.
The common trap on this topic
The most common CLAT error is failing to first resolve an inner phrase like 'my mother's only daughter' or 'my father's only son' before assigning the outer relation, which leads students to treat these phrases as referring to some unnamed third person instead of collapsing them to the speaker or a close relative already in the tree. A second frequent trap is losing track of gender partway through a long chain - for example, correctly identifying a person as the speaker's parent's sibling's child, but then mislabeling that person as a nephew instead of a cousin because the generation level was miscounted by one step. A third and very specific trap appears in symbolic-code questions: students apply the operators in the wrong order, computing the relation from the last symbol backwards instead of strictly left to right as the code chain is written, which silently reverses who is related to whom and produces a plausible-sounding but incorrect answer such as swapping 'mother-in-law' for 'daughter-in-law'.
Take the micro-test
Introducing a man, a woman said, 'His mother is the only daughter of my mother.' How is the woman related to the man?
Pointing to a photograph, a man said, 'She is the daughter of my grandfather's only son.' Assuming the man is that only son's child, how is the girl in the photograph related to the man?
A is B's brother. C is B's mother. D is C's father. E is D's mother. How is A related to D?
Pointing to a man, a woman said, 'His son is my son's father.' How is the woman related to the man?
P is the son of Q. Q and R are siblings with the same mother. S is R's mother. How is S related to P?
Introducing a boy, a girl said, 'He is the son of my father's only daughter.' Given the girl is her father's only daughter, how is the boy related to the girl?
A's mother is the sister of B. B has a son, C. How is C related to A?
Pointing to a lady, a man said, 'Her husband is the only son of my wife's mother.' How is the lady related to the man?
Introducing a man, a woman said, 'He is the only grandson of my father.' The woman has no brothers and only one child. How is the man related to the woman?
If A + B means A is the mother of B, A - B means A is the brother of B, and A x B means A is the wife of B, and it is given that P + Q, Q - R, and R x S, how is P related to S?
FAQ
What does 'my mother's only daughter' usually mean if the speaker is female?
It almost always resolves to the speaker herself, since being her mother's only daughter means no other daughter exists in that family, so the phrase simply refers back to the speaker.
How should I read a symbolic code like 'A + B - C × D' in blood relation questions?
Strictly left to right, resolving one operator at a time and carrying the result forward - determine what A + B means first, then apply the next operator to that result and C, and so on, rather than jumping to the last symbol first.
Why do CLAT blood relation questions specify 'only son' or 'only daughter' so often?
Because that word is what allows an otherwise ambiguous phrase to collapse to one specific, already-identified person; without 'only', the referenced person could be any of several siblings and the question would have no single correct answer.
Keep practising
- → Syllogisms
- → Statement and Assumption
- → Strengthen and Weaken Arguments
- → All Logical Reasoning practice
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