Blood Relations — SSC CGL Reasoning

Blood relation questions are never hard — they are tangled. "The daughter of the only son of my grandfather" is three hops, and SSC bets you will try to hold all three in your head. The counter-strategy is mechanical: parse from the end of the phrase, draw one symbol per person, and never assume a gender the sentence didn't state.

1. What SSC actually asks

Tier 1: 1–2 Q · Tier 2: 1–2 Q. Three formats dominate:

1. Pointing / introducing — "Pointing to a photograph, Ravi said, 'She is the daughter of…'". Decode a nested phrase.
2. Coded relations — "A + B means A is the mother of B" — translate an expression like $P\times Q+S$ into a relationship.
3. Mini family trees — 4–6 people, 3–4 statements, one question ("How is E related to C?").

2. The drawing convention

• Square = male, circle = female, ? = gender unknown.
• Vertical line = parent above, child below. Double horizontal line = married couple. Single dash = siblings.
• Keep each generation on its own row — most wrong answers put an uncle in the wrong row.

The golden rule: never assume gender. "P is the child of Q" leaves P's gender open; "cousin", "child", "sibling" and "spouse's parent" questions frequently have "cannot be determined" as the honest — and correct — answer.

3. Parsing nested phrases: work backwards

Decode "the daughter of the only son of my grandfather" from the right:

1. my grandfather → draw him.
2. the only son of my grandfather → my father (the "only" kills the uncle possibility).
3. the daughter of my father → my sister (or me, if I am female).

Watch the word "only" — it is doing load-bearing work. "The only son" forces father; without "only", the son could be an uncle and the question usually becomes ambiguous. SSC includes "only" precisely so a unique answer exists.

4. Coded relations: translate right-to-left

Given codes like A + B = A is the mother of B, an expression $P\times Q+S$ reads pair-by-pair:

• $P\times Q$: P is the father of Q.
• $Q+S$: Q is the mother of S.
• Chain: P → Q → S with Q female ⇒ P is the maternal grandfather of S.

Draw the mini-tree as you translate; do not chain in your head. The maternal/paternal distinction lives in the middle person's gender.

5. Solved PYQ-style examples

Q1. Pointing to a photograph, Ravi said, "She is the daughter of my grandfather's only son." How is the girl related to Ravi? Solution. Grandfather's only son = Ravi's father. His daughter = Ravi's sister.

Q2. A woman pointing to a man says, "His mother is the only daughter of my mother." How is the woman related to the man? Solution. "Only daughter of my mother" = the speaker herself. So his mother is the speaker: she is his mother. (The classic self-reference trap — the phrase loops back to the speaker.)

Q3. A is the brother of B. B is the sister of C. C is the father of D. How is A related to D? Solution. A, B, C are siblings; A is male; C is D's father → A is D's uncle.

Q4. A ÷ B means A is the mother of B; A × B means A is the father of B. What does $P\times Q÷S$ tell about P? Solution. P is Q's father; Q is S's mother → P is S's maternal grandfather (Q, the middle link, is female).

Q5. A is married to C. D is the son of A. B is the brother of C. E is the daughter of D. How is E related to C? Solution. Rows: (C = A) with B beside C; below them D; below D, E. D is C's son, E is D's daughter → E is C's granddaughter.

6. Exam protocol

1. Draw for every question — squares, circles, generation rows. The 15 seconds of drawing beats a 2-mark loss.
2. Parse nested phrases from the last word backwards, one hop per symbol.
3. Circle the word "only" when it appears — it is what makes the answer unique.
4. In coded expressions, resolve pairs right-to-left and note the middle person's gender for maternal/paternal.
5. Before marking uncle/aunt/cousin/grandchild, re-check the stated genders. If a needed gender was never given, the answer is "cannot be determined" — and SSC does list it.