Blood relations for IBPS Clerk

Blood relation questions describe family links in words and ask how two people are related. They look like riddles, but they are really small diagrams. If you draw the family tree, the answer is usually in front of you within a few seconds. If you try to hold the tree in your head, one "my mother's only son" is enough to trip you.

This topic appears on its own in the prelims and gets folded into bigger puzzles in the mains, where a family of six or eight people is spread across floors or seats. The drawing habit you build here carries straight into those sets.

How to draw the tree

Keep each generation on one level: grandparents at the top, parents in the middle, children at the bottom. Most relation words are fixed by two things only: the generation gap and the gender.

Gender comes only from the question

Never decide anyone's gender from a name. A person is male only if the question calls them a son, brother, father, husband, uncle, nephew, "he", "this man" and so on. A person is female only if the question calls them a daughter, sister, mother, wife, aunt, niece, "she", "this woman" and so on.

If the question does not say, the gender is unknown, and that is often the whole point of the question. "Child" is not the same as "son". "Sibling" is not the same as "brother".

Worked examples

Example 1 (direct). A is the brother of B. B is the daughter of C. How is A related to C?

1. "Brother" makes A male. "Daughter" makes B female.
2. B is C's child, and A is B's sibling, so A is also C's child.
3. A is C's son.

Example 2 (photograph). Pointing to a photograph, a woman says, "This man is the son of my mother's only son." How is the man related to the woman?

1. The speaker is a woman, so she cannot be her mother's son. Her mother's only son is her brother.
2. The man in the photograph is her brother's son.
3. He is her nephew.

Example 3 (why stated gender matters). Pointing to a man, R says, "His mother is the only daughter of my mother." R is male. How is R related to the man?

1. R is male, so "the only daughter of my mother" is R's sister, not R.
2. The man's mother is R's sister, so R is the brother of the man's mother.
3. R is the man's maternal uncle.

Now suppose the question had said R is female. Then "the only daughter of my mother" would be R herself, and R would be the man's mother. One word about gender changes the answer completely. This is why you never guess.

Coded relations

Some questions replace relations with symbols. For the examples below:

• A + B means A is the mother of B.
• A − B means A is the brother of B.
• A × B means A is the father of B.
• A ÷ B means A is the sister of B.

Read a coded chain from left to right, one link at a time, and draw each link as you go.

Example 4. What does P + Q − R mean?

1. P + Q: P is the mother of Q. P is female.
2. Q − R: Q is the brother of R. Q is male, and R is P's child too.
3. P is the mother of R. R's gender is not given.

Example 5. Which expression shows that J is the grandmother of L? (a) J + K × L (b) J × K + L (c) J − K + L

1. (a) J is the mother of K, and K is the father of L. J is L's grandmother. It works.
2. (b) J is the father of K. J is male, so J cannot be a grandmother.
3. (c) J is the brother of K, and K is the mother of L. J is L's maternal uncle, not a grandparent.
4. (a).

Family puzzles

Example 6. A family has six members: P, Q, R, S, T and U.

• P is the husband of Q.
• R is the son of P and Q.
• S is the sister of R.
• T is the wife of R.
• U is the son of R and T.

Questions: How is S related to U? How is Q related to T? How many male members are there?

1. Mark genders from the words: P male (husband), Q female, R male (son), S female (sister), T female (wife), U male (son).
2. Draw three levels: P = Q at the top; R = T and S in the middle; U at the bottom under R and T.
3. S is the sister of U's father, so S is U's aunt (father's sister).
4. Q is the mother of T's husband, so Q is T's mother-in-law.
5. The males are P, R and U. Three.

Common mistakes

• Reading gender into a name. Only relation words, "he", "she", "man" and "woman" tell you gender.
• Collapsing "child" into "son" because it feels natural. If the question does not say, the answer may be "cannot be determined".
• Missing that the speaker can be the person described. "My mother's only son", spoken by a man, is the speaker himself.
• Placing two people on the same level when one is a generation above. Draw the levels before the lines.

Practice

Aim for six minutes. Use the codes from the coded relations section where needed.

1. M is the sister of N. N is the son of O. How is M related to O?
2. X is the husband of Y. Z is the son of Y's only brother. How is X related to Z?
3. What does P × Q + R mean?
4. Pointing to a woman, a man says, "She is the daughter of the only child of my grandmother." How is the woman related to the man?
5. K is the mother of L and M. N is the husband of K. L is male; M's gender is not given. (a) How is N related to M? (b) How is M related to L?
6. What does A ÷ B + C mean?
7. E is the son of F. F is the daughter of G. H is the husband of G. How is H related to E?
8. Pointing to a photograph, V says, "This person's father is the only son of my father." V is female. How is the person related to V?

Answers:

1. Daughter. "Sister" makes M female, and M shares N's parent O.
2. Uncle. Z is Y's brother's son, so Z is Y's nephew. X is Y's husband, so X is Z's uncle by marriage (father's sister's husband).
3. P is the grandfather of R. P is the father of Q, and Q is the mother of R. P is male, and on R's mother's side.
4. Sister. The only child of the man's grandmother must be one of his parents. That parent's daughter is his sister.
5. (a) Father. N is male (husband) and married to M's mother. (b) Sibling. M's gender is not given, so you cannot say brother or sister.
6. A is the maternal aunt of C. A is the sister of B (A is female), and B is the mother of C.
7. Maternal grandfather. H is G's husband, so H is F's father. F is E's mother, so H is E's mother's father.
8. Nephew or niece. V is female, so the only son of V's father is V's brother. The person is V's brother's child, and the person's gender is not stated. If V had been male, the "only son" could be V himself, and the person would be V's own child.

What to do next

• Draw a tree for every question this week, even two-line ones. Speed comes from the drawing habit, not from skipping it.
• Make a two-column list of relation words by gender and generation, and test yourself until you can place any word in one second.
• Try 10 coded questions and 3 family puzzles, then move to floor and box puzzles, where family clues often appear.
• Revise direction sense next. The mains sometimes combines the two in one question.