Blood Relations

Snapshot

• Blood Relations gives a chain of family clues ("A is the son of B, who is the sister of C ...") and asks how two people are related. It needs no formulas, only a clear method.
• The winning habit is to draw a small family tree instead of holding the chain in your head. A tree turns a tangled sentence into a path you can read off.
• CUET uses direct chains, pointing-at-a-photograph statements, coded relations with symbols, family puzzles with several people, counting questions and "cannot be determined" cases.
• Two rules prevent almost every error: fix gender only when the sentence fixes it, and count generations strictly. Exam reality: +5 for a correct answer and −1 for a wrong one.

Part 1 — The tree method

Written and reviewed by Devendra Dubey, Mathematics & Commerce faculty at UniDrill (M.Sc. Mathematics, Osmania University · 10 years teaching). Prepared for the CUET UG General Test.

A family is a tree. If you draw it the same way every time, you never lose track.

In the tree above, A and B are a married couple, with children C and E. C is married to D, and their children are F and G. Reading the tree: F is B's grandson, E is F's paternal aunt (bua), and D is G's mother.

Drawing steps.

Part 2 — The full menu of blood-relation questions

Part 3 — The kinship dictionary

Learn this table until each row is automatic. Questions often use the Indian terms in brackets.

Neutral words. Sibling, spouse, parent, child, cousin and in-law do not tell you gender. Do not assume one.

Part 4 — The two rules that prevent every error

Rule 1: gender. Mark a person male or female only when the sentence tells you. "A is the brother of B" makes A male but leaves B's gender open. "A is the sister of B" makes A female, B open. "A is the husband of B" makes A male and B female.

Rule 2: generations. Same row means siblings, spouses or cousins. One row up is a parent, uncle or aunt. Two rows up is a grandparent. Most wrong answers come from slipping a row, so say the generation aloud as you add each person.

Side matters. Father's side and mother's side give different words: father's sister is a bua; mother's sister is a mausi. Always check which parent the link runs through, and give the side only when the clues fix it.

Part 5 — Pointing and single-person statements

Statements like "Pointing to a man, Reena said, 'He is the son of ...'" are solved by anchoring on the speaker. Treat "I", "me" and "my" as the root of your tree and move outward one phrase at a time.

Classic: a man says, "I have no brother or sister, but that man's father is my father's son." My father's son is a male child of my father. Since I have no brother or sister, my father's only son is me. So that man's father is me, and the man is my son.

Classic: "Pointing to a girl, a man said, 'She is the daughter of my father's only son.'" The speaker is male, so his father's only son is himself. The girl is his daughter.

Classic: "Pointing to a lady, a man said, 'Her mother is the only daughter of my mother.'" The only daughter of my mother is my sister. The lady's mother is my sister, so the lady is my sister's daughter, my niece.

Pause and predict: A woman points to a man and says, "He is the only son of my mother's father." How is the man related to her?

Check your answer: My mother's father is my maternal grandfather. His only son is my mother's brother, so the man is her maternal uncle (mama).

Part 6 — Coded relations

Symbols stand for relations. First write the key, then translate left to right, building a tiny tree as you go.

Suppose: A + B means A is the father of B, A − B means A is the sister of B, A × B means A is the wife of B, A ÷ B means A is the brother of B.

Why P is S's mother. P is the wife of Q, and Q is the father of R. R and S are siblings. So Q is the father of S as well, and P is S's mother.

Be careful with gender. In P × Q + R − S, the symbol × makes P female and Q male. In M ÷ N + O, the symbol ÷ makes M male, but N has no stated gender; the next symbol + (father) makes N male.

Part 7 — Family puzzles

When many people appear, use a quick table or a tree. The following puzzle is a typical size.

Puzzle. Six members A, B, C, D, E and F are in a family. A is the husband of B. C is the son of B. D is the wife of C. E is the daughter of D. F is the brother of A.

Part 8 — Counting questions

These use simple equations. Let b be the number of boys and g the number of girls.

Example. Ravi says: "I have as many brothers as sisters. Each of my sisters has twice as many brothers as sisters." Ravi is a boy, so he has (b − 1) brothers and g sisters, giving b − 1 = g. A sister has b brothers and (g − 1) sisters, giving b = 2(g − 1). Substitute: g + 1 = 2g − 2, so g = 3 and b = 4. The family has 4 boys and 3 girls.

Part 9 — Worked examples with full reasoning

1. A is the brother of B. B is the sister of C. C is the father of D. How is A related to D? A is male (brother) and a sibling of B. B is also a sibling of C. So A and C are siblings, and C is the father of D. A is D's paternal uncle.

2. P is the mother of Q. Q is the sister of R. R is the father of S. How is P related to S? Q and R are siblings, so P is the mother of R as well. R is the father of S, so P is S's grandmother on the father's side: the paternal grandmother.

3. Pointing to a photograph, a man said: "I have no brother or sister, but that man's father is my father's son." Whose photograph is it? My father's son is me (I have no brother). So that man's father is me. The photograph is of my son.

4. Pointing to a girl, a man said: "She is the daughter of my father's only son." How is the girl related to the man? The man's father's only son is the man himself. So the girl is his daughter.

5. A's mother is the only daughter of B's father, and B is a male. How is B related to A? B's father has one daughter, who is A's mother. B is another child of that father, and a male, so he is the brother of A's mother. B is A's maternal uncle (mama).

6. X is the son of Y. Y is the wife of Z. Z is the son of W. W is a male. How is W related to X? Y is X's mother and Z is X's father. W is the father of Z, so W is X's paternal grandfather (dada).

7. Coded relations with the key from Part 6. P × Q + R − S. How is P related to S? P is the wife of Q. Q is the father of R. R is the sister of S. So Q is the father of S and P is the mother of S.

8. The puzzle in Part 7: how is F related to E? F is the brother of A. A is the father of C and C is the father of E. So F is the brother of E's grandfather, a grand-uncle (dada's brother).

9. A is B's sister. C is B's mother. D is C's father. How is A related to D? A and B are siblings, so C is also A's mother. D is C's father, so D is the maternal grandfather of A. A is D's granddaughter (A is female because she is called a sister).

10. Pointing to a lady, a man said: "Her mother is the only daughter of my mother." How is the lady related to the man? The only daughter of my mother is my sister. The lady's mother is my sister, so the lady is my sister's daughter: my niece.

11. X is the brother of Y's wife. How is X related to Y? Y's wife's brother is a brother-in-law, so X is Y's brother-in-law.

12. A is a sibling of B. B is a parent of C. How is A related to C? The gender of A is not stated, so A is C's uncle if male and C's aunt if female. The gender of B is also missing, so the side (father's or mother's) is open too. The most you can say is uncle or aunt; if the options include "cannot be determined", choose it.

13. A man has three sons, and each son has exactly one sister. How many people are in the family (the man, his wife and their children)? Each son has exactly one sister, so the family has one daughter. The count is 1 man + 1 wife + 3 sons + 1 daughter = 6.

14. What is the relation of the son of my mother's brother to me? Mother's brother is a maternal uncle. His son is my cousin (maternal uncle's son).

Part 10 — Common traps

Part 11 — Rapid-fire practice

Draw a mini tree for each. Answers follow.

Part 12 — A timed-practice routine

If a question stays tangled after 60 seconds, mark it, move on and return. The negative mark makes a blind guess costly.

One-line revision: draw a square-and-circle tree by generation, fix gender only when the clue does so, keep rows strict, and translate coded symbols and kinship terms before reading off the answer.

Part 13 — Where this connects

Family-tree thinking is close to the diagrams in Direction Sense and Ranking & Arrangement, where a sketch also replaces memory. The "chain of statements" logic returns in Syllogism, and symbol keys echo Coding-Decoding.