Blood relations for IBPS PO

Blood relation questions are short, but they punish one habit more than any other: guessing someone's gender. A letter tells you nothing. A name tells you nothing. Only a relation word (father, sister, wife, son) tells you, and when a question does not give one, the correct answer may be "cannot be determined".

IBPS PO uses three forms: family puzzles with several members, coded relations built from symbols, and "pointing to a person" statements. The same diagram method handles all three.

The diagram

Draw every relation in the same way, so your eye can read the tree at a glance.

Useful terms to have ready:

• Paternal means on the father's side; maternal means on the mother's side.
• In-law means related through a marriage: a spouse's parent, sibling or a sibling's spouse.
• Nephew and niece are a sibling's son and daughter; uncle and aunt are a parent's brother and sister (or their spouses).

Worked example 1: a family puzzle

A family has seven members, K, L, M, N, O, Q and R, across three generations. There are two married couples.

1. K is the husband of M. M is the mother of O.
2. L is the only brother of O.
3. Q is the son of L.
4. R is the sister of Q.
5. N is the mother of R.
6. O is unmarried and is an aunt of R.

Building the tree

• Clue 1: K is male and M is female, a married couple. O is their child.
• Clue 2: L is male and a child of K and M.
• Clue 3: Q is male, the son of L.
• Clue 4: R is female, Q's sister, so also L's child.
• Clue 5: N is female, R's mother, so N is L's wife. That is the second couple.
• Clue 6: O is female (an aunt).

Top generation: K (male) = M (female). Middle: L (male) = N (female), and O (female). Bottom: Q (male) and R (female), children of L and N.

Questions

1. How is N related to K? Daughter-in-law (wife of K's son L).
2. How is O related to Q? Aunt, specifically his father's sister.
3. How is R related to M? Granddaughter.
4. How many female members are there? Four (M, N, O and R).
5. How is K related to R? Grandfather (paternal).

Worked example 2: coded relations

Suppose:

Different letters are different people.

Question: In P + Q × R ÷ S, how is Q related to S?

• P + Q: P is Q's father (P male).
• Q × R: Q is R's brother (Q male).
• R ÷ S: R is S's daughter (R female).
• Q and R are siblings, so S is Q's parent too. Q is male.
• Answer: Q is S's son. P is the father of both, so S is their other parent. No code states S's gender, so do not assume it.

Worked example 3: a longer code

Using the same codes: in T − O × K ÷ M − N, how is M related to T?

• T − O: T is O's wife (T female).
• O × K: O is K's brother (O male).
• K ÷ M: K is M's daughter, so O is M's son.
• M − N: M is N's wife, so M is female.
• M is the mother of T's husband. Answer: M is T's mother-in-law.

Worked example 4: pointing to a person

Pointing to a woman, a man says, "Her mother is the only daughter of my mother."

• "The only daughter of my mother" is the man's sister.
• The woman's mother is his sister, so the woman is his sister's daughter.
• Answer: she is his niece.

Worked example 5: the "only son" trap

Pointing to a boy, a man says, "He is the son of my father's only son."

• The man is male and is his father's son. If his father has only one son, that son is the man himself.
• So the boy is the man's own son.
• Answer: son.

Common mistakes

• Assuming gender from a letter or a name. Mark + or − only from a relation word.
• Mixing up generations. Draw levels; do not hold the tree in your head.
• Forgetting that "only son" or "only daughter" can mean the speaker.
• Reading a coded chain right to left. Each symbol links the letter before it to the letter after it.
• Missing the in-law step. A spouse's parent is an in-law, not a parent.

Practice set

1. M is the brother of N. N is the daughter of O. O is the wife of P. How is M related to P?
2. Using the codes above, what does A − B + C tell you about A and C?
3. Using the codes above, what does X × Y ÷ Z tell you about X and Z?
4. In worked example 1, how is O related to N?
5. Introducing a woman, a man says, "She is the wife of the only son of my father." How is the woman related to the man?
6. Using the codes above, in D + E × F − G, how is D related to G?
7. Pointing to a girl, a woman says, "She is the daughter of the only child of my mother." How is the girl related to the woman?

Answers

1. Son. M is male (brother). O is N's parent, and P, O's spouse, is N's other parent. So M is P's son.
2. A is C's mother. A is B's wife, and B is C's father.
3. X is Z's son. X is male (brother) and a sibling of Y, whose parent is Z.
4. Sister-in-law. O is the sister of L, and N is L's wife.
5. His wife. The only son of the man's father is the man himself.
6. Father-in-law. D is the father of E, E is F's brother, so F is D's daughter. F is G's wife.
7. Daughter. The woman is a child of her mother; if her mother has only one child, that child is the woman herself.

What to do next

• Redraw worked example 1 with + and − marks, and check that every mark came from a word in the clues.
• Solve ten coded-relation questions, writing each symbol's meaning above the chain before you read it.
• Revise floor and box puzzles, where family trees often appear as an extra layer, and data sufficiency in reasoning, where gender traps are common.