Module 2 · SSC CGL Reasoning
Blood Relations
Family trees, coded relations.
Family Trees · Coded Relations
Learning Objectives
- Understand the fundamental concepts of Blood Relations
- Apply key formulas and techniques to solve problems
- Practice with exam-level questions to build speed and accuracy
Key Concepts
What is a Blood Relation?
A blood relation connects two individuals through birth (parent-child, siblings) or through marriage (husband-wife, in-laws). SSC CGL exam tests your ability to decode family trees, interpret coded relations, and answer questions about how two people are related.
Family Tree Method
Always draw a family tree when solving blood relation problems. Use these standard symbols:
- Square (□) = Male
- Circle (ˆ) = Female
- Horizontal line (—) = Marriage
- Vertical line (|) = Parent-child
- Same generation = Place names at same level
Tip 1: Universal Family Tree Symbols
Draw a square for every male and a circle for every female. Connect married couples with a horizontal line. Draw vertical lines from parents down to children. Label each node with the person's name or letter. This visual approach prevents mistakes in complex problems.
Standard family tree notation: Square = Male, Circle = Female
Complete Relation Dictionary
Memorise this comprehensive table of family relations. SSC CGL questions assume you know these by heart.
| Relation | Definition |
| Father | Male parent |
| Mother | Female parent |
| Brother | Male sibling (same parents) |
| Sister | Female sibling (same parents) |
| Husband | Male spouse |
| Wife | Female spouse |
| Son | Male child |
| Daughter | Female child |
| Grandfather | Father's father or mother's father |
| Grandmother | Father's mother or mother's mother |
| Uncle | Father's brother / Mother's brother / Husband of aunt |
| Aunt | Father's sister / Mother's sister / Wife of uncle |
| Cousin | Child of uncle or aunt |
| Nephew | Sister's son or brother's son |
| Niece | Sister's daughter or brother's daughter |
| Father-in-law | Wife's father or husband's father |
| Mother-in-law | Wife's mother or husband's mother |
| Brother-in-law | Wife's brother / Husband's brother / Sister's husband |
| Sister-in-law | Wife's sister / Husband's sister / Brother's wife |
| Son-in-law | Daughter's husband |
| Daughter-in-law | Son's wife |
Tip 2: Memorise the Dictionary
Create flashcards for the 20 common relations listed above. SSC CGL examiners often test multiple relations in a single chain like "father's sister's husband" = uncle. You must fluently translate such phrases.
Paternal vs Maternal Relations
Understanding the father's side (paternal) versus mother's side (maternal) is critical:
- Paternal = Related through father (paternal grandfather = father's father)
- Maternal = Related through mother (maternal uncle = mother's brother)
- Paternal aunt = Father's sister
- Maternal aunt = Mother's sister
- Paternal uncle = Father's brother
- Maternal uncle = Mother's brother
Example 1 (Paternal vs Maternal)
A is the son of B. C is the brother of B. D is the daughter of C. How is A related to D?
a) Cousin brother b) Cousin sister c) Uncle d) Brother
a) Cousin brother b) Cousin sister c) Uncle d) Brother
Solution: a) Cousin brother. A is son of B. C is brother of B, so C is A's paternal uncle. D is daughter of C. So A and D are children of siblings (B and C). They are cousins. Since A is male and D is female, A is D's cousin brother.
Tip 3: Paternal vs Maternal Trick
When you see "father's side" think PATERNAL. When you see "mother's side" think MATERNAL. In SSC exams, they may use phrases like "my father's only son" — that means the speaker himself (if male) or the speaker's brother (if female). "Only son" means there are no other brothers.
Spouse Relations
Marriage creates new relationships without blood connection. Key patterns:
- Spouse of blood relative becomes in-law (e.g., sister's husband = brother-in-law)
- Blood relative of spouse becomes in-law (e.g., husband's brother = brother-in-law)
- Spouse's sibling's spouse has no direct relation (e.g., wife's sister's husband = no relation, unless both couples are related)
Example 2 (Spouse Relation Chain)
A is the husband of B. C is the brother of A. D is the wife of C. How is B related to D?
a) Sister b) Sister-in-law c) Cousin d) No relation
a) Sister b) Sister-in-law c) Cousin d) No relation
Solution: b) Sister-in-law. A is B's husband. C is A's brother. D is C's wife. So B and D are married to two brothers (A and C). Hence B and D are sisters-in-law to each other (brothers' wives).
Tip 4: Spouse Relation Flowchart
Draw a horizontal line for every marriage. Connect each spouse pair. Then trace from one person to another through the tree. If you cross a marriage line, the relation is "in-law" (unless you cross back through a blood relation).
Pointing / Photograph Questions
In these questions, one person points to a photograph or another person and describes a relationship. The relationship is always from the speaker's perspective unless stated otherwise.
Tip 5: Pointing Questions — Who is the Speaker?
Always identify the speaker first. The sentence "A said, pointing to B, 'He is the father of my sister'" means the relation "father of my sister" is from A's perspective. "My" refers to the speaker A. Father of A's sister = A's father. So B is A's father.
Example 3 (Pointing Question)
A man pointed to a photograph and said, "She is the daughter of the only son of my mother." How is the woman in the photograph related to the man?
a) Sister b) Daughter c) Niece d) Mother
a) Sister b) Daughter c) Niece d) Mother
Solution: b) Daughter. "My mother" = speaker's mother. "Only son of my mother" = the speaker himself (since he is the only son). "Daughter of the only son" = daughter of the speaker. So the woman is the speaker's daughter.
Example 4 (Photograph Question)
A woman pointed to a man and said, "He is the brother of my mother's only daughter." How is the man related to the woman?
a) Brother b) Uncle c) Cousin d) Father
a) Brother b) Uncle c) Cousin d) Father
Solution: a) Brother. "My mother's only daughter" = the woman herself (if she is the only daughter of her mother). "Brother of ..." = brother of the woman. So the man is the woman's brother.
Tip 6: "Only" is the Key
Words like "only son," "only daughter," "only child" are critical. "Only son of my father" means the speaker (if male) or the speaker's brother (if female, and the father has only one son). "Only daughter" similarly identifies a unique female child.
Coded Blood Relations
SSC CGL frequently asks coded relation problems where symbols represent relationships. Common codes:
- A + B = A is the mother of B
- A - B = A is the father of B
- A × B = A is the brother of B
- A ÷ B = A is the sister of B
- A = B = A is the wife of B
- A & B = A is the husband of B
Tip 7: Decode Coded Relations Step by Step
Read from left to right. For 'A - B + C', first identify A's relation to B (A is father of B), then B's relation to C (B is mother of C). Combine: A is father of B, who is mother of C, so A is maternal grandfather of C. Track genders at each step.
Example 5 (Basic Coded Relation)
If 'P + Q' means P is the father of Q, 'P - Q' means P is the mother of Q, 'P × Q' means P is the brother of Q, 'P ÷ Q' means P is the sister of Q, then what does 'A + B × C' mean?
a) A is the uncle of C b) A is the father of C c) C is the nephew of A d) A is the brother of C
a) A is the uncle of C b) A is the father of C c) C is the nephew of A d) A is the brother of C
Solution: c) C is the nephew of A. A + B = A is father of B. B × C = B is brother of C. So A is father of B, B is brother of C. Since B and C are siblings, A is the father of both. Therefore C is the son or daughter of A. But B is C's brother, so C could be male or female. Among options, 'C is the nephew of A' would mean C is male and A is C's uncle. That is wrong because A is C's father. Actually: A is father of B, B is brother of C, so C is also A's child. So C is A's son/daughter. None of the options say son/daughter. Let me check: c says 'C is the nephew of A'. If C is A's child, C cannot be A's nephew. Actually I need to re-express: B is brother of C means B and C are siblings. A is father of B, so A is also father of C. So C is A's child, not nephew. The answer is that A is the father of C, option b.
Example 6 (Coded Chain)
If 'A × B' means A is the sister of B, 'A + B' means A is the mother of B, 'A - B' means A is the father of B, 'A = B' means A is the wife of B, what does 'P = Q - R × S' mean?
a) P is the grandmother of S b) P is the mother of S c) S is the granddaughter of P d) P is the aunt of S
a) P is the grandmother of S b) P is the mother of S c) S is the granddaughter of P d) P is the aunt of S
Solution: a) P is the grandmother of S. P = Q means P is wife of Q. Q - R means Q is father of R. R × S means R is sister of S. So P and Q are married. Q is father of R and S (since R and S are siblings). So P is the mother of R and S. Therefore P is the mother of S, not grandmother. Wait: Q is father of R, R is sister of S. So R and S are both children of Q. P is Q's wife, so P is the mother of R and S. So P is mother of S, option b.
Tip 8: Build From the Last Statement
SSC shortcut: For expressions like 'A + B × C - D', start from the LAST operation. Identify C - D first, then B × (C - D), then A + (result). This avoids confusion about operator precedence. Alternatively, work left to right but keep a running family tree.
SSC Shortcut Techniques
Tip 9: Generation Level Method
Assign generation numbers: Self = 0, Parents = +1, Grandparents = +2, Children = -1, Grandchildren = -2, Siblings = 0, Spouse = same as partner. Sum the generational differences. A difference of +2 means the person is two generations older (grandparent). Difference of -1 means one generation younger (child/nephew/niece).
Tip 10: "Of" Indicates Direction
"Father of B" means A is the father, B is the child. Read "A is the father of B" as A → B (A to B). The word "of" points from the older/owner to the younger/owned. Similarly "son of A" points from the child to the parent.
Tip 11: Gender Marking
Always mark the gender of each person as you decode. If the relation describes someone as "brother," "father," "husband," "son," "uncle," "nephew" — they are MALE. "Sister," "mother," "wife," "daughter," "aunt," "niece" — they are FEMALE. Unmarked genders often become the trick in the question.
Tip 12: "Only Child" Deductions
If X is the "only son of Y," then X has no brothers. If X is "only daughter of Y," then X has no sisters. If X is "only child of Y," then X has no siblings at all. These constraints help eliminate possibilities in family tree reconstruction.
Tip 13: Draw Incrementally
Add one relationship at a time to your family tree. Start with the first sentence, draw it. Then add the second, then the third. If you try to hold everything in your head, you will make mistakes. A well-drawn tree takes 10 seconds and prevents errors.
Tip 14: Verify the Reverse
After you calculate a relation, verify it in reverse. If you think P is Q's uncle, check: is Q P's nephew/niece? A correct relation always works both ways. This catches half the mistakes.
Tip 15: Practice Mock Timed Sets
Blood relation questions in SSC CGL Tier 1 typically take 30-45 seconds each. Practice with a timer. If a question takes more than 60 seconds, mark and move on. Speed comes from pattern recognition, not calculation speed.
Solved Examples
Example 7 (Direct Blood Relation)
A is the father of B. C is the daughter of B. D is the son of C. How is A related to D?
a) Great-grandfather b) Grandfather c) Uncle d) Father
a) Great-grandfather b) Grandfather c) Uncle d) Father
Solution: a) Great-grandfather. A → B (father). B → C (daughter), so B is parent of C. C → D (son), so C is parent of D. A is parent of B, B is parent of C, C is parent of D. A is two generations above D, making A D's great-grandfather.
Example 8 (Coded with Negation)
If 'A @ B' means A is the father of B, 'A # B' means A is the mother of B, 'A $ B' means A is the brother of B, 'A % B' means A is the sister of B, then what does 'P # Q $ R @ S' mean?
a) P is the grandmother of S b) P is the mother of S c) S is the granddaughter of P d) P is the aunt of S
a) P is the grandmother of S b) P is the mother of S c) S is the granddaughter of P d) P is the aunt of S
Solution: a) P is the grandmother of S. P # Q = P is mother of Q. Q $ R = Q is brother of R. R @ S = R is father of S. So P is mother of Q, Q is brother of R, R is father of S. Thus: P and her husband had children Q and R. Q is male (brother), R is male (father). R has child S. So P is the grandmother of S (mother's side, specifically paternal grandmother since R is son of P and father of S).
Example 9 (Multiple Generations)
A is the mother of B. C is the husband of A. D is the sister of C. E is the wife of D. How is E related to B?
a) Aunt b) Mother c) Sister-in-law d) No relation
a) Aunt b) Mother c) Sister-in-law d) No relation
Solution: a) Aunt. A is mother of B. C is husband of A, so C is father of B. D is sister of C, so D is paternal aunt of B. E is wife of D. So E is the wife of B's paternal aunt. In common terms, E is also considered B's aunt (aunt by marriage).
Advanced Example Problems
Advanced Example 1 (Complex Family Tree)
A and B are married. A is the father of C. C is married to D. D is the sister of E. E is the father of F. F is the brother of G. How is G related to A?
a) Granddaughter b) Grandson c) Cannot be determined d) Niece
a) Granddaughter b) Grandson c) Cannot be determined d) Niece
Solution: a) Granddaughter. A (male) and B (female) are married. A is father of C. So C is child of A and B. C is married to D. D is sister of E, so D and E are siblings. E is father of F. F is brother of G, so F and G are siblings. So E is father of both F and G. Since D is sister of E, G is the child of E, making G the niece/nephew of D. But D is married to C, who is child of A. So G is the child of D's brother. Therefore G is not directly related to A by blood. However, through marriage: D is daughter-in-law of A, and G is D's niece/nephew. There's no direct relation. But wait — the question asks "How is G related to A?" G is not a blood relative of A. But among options, "Granddaughter" is listed. Let me re-trace: A is father of C. C married to D. D's brother E has children F and G. So G is not related to A by blood. Option c) Cannot be determined is the answer. BUT if C is male, then D is female. D's brother E is male, E's children F and G are E's kids. G is the niece/nephew of D, so G is the niece/nephew of A's daughter-in-law. No direct relation to A. Answer: c) Cannot be determined.
Advanced Example 2 (Pointing with Coded Relation)
A man said, "This boy is the son of my mother's only daughter's husband." How is the boy related to the man?
a) Nephew b) Son c) Brother d) Cousin
a) Nephew b) Son c) Brother d) Cousin
Solution: a) Nephew. "My mother" = man's mother. "Only daughter of my mother" = the man's sister (if he has only one sister, or he himself if he is female — but the speaker is male, so "my mother's only daughter" is his sister). "Husband of my mother's only daughter" = husband of his sister = his brother-in-law. "Son of my mother's only daughter's husband" = son of his brother-in-law. But the brother-in-law's son would be the sister's son = the man's nephew. So the boy is the man's nephew.
Advanced Example 3 (Mixed Codes)
If 'A & B' means A is the brother of B, 'A | B' means A is the wife of B, 'A ^ B' means A is the father of B, 'A ~ B' means A is the daughter of B, then what does 'P & Q | R ^ S ~ T' mean in terms of P and T?
a) P is the uncle of T b) P is the brother of T c) T is the niece of P d) Cannot be determined
a) P is the uncle of T b) P is the brother of T c) T is the niece of P d) Cannot be determined
Solution: d) Cannot be determined. P & Q = P is brother of Q. Q | R = Q is wife of R. R ^ S = R is father of S. S ~ T = S is daughter of T. So: P is brother of Q. Q is married to R. R is father of S, so S is child of R. S is daughter of T, so T is parent of S. Since R is father of S and T is also parent of S, T must be R's wife (assuming standard family). But wait, Q is R's wife. So if T is also R's wife, that would mean R has two wives, which is not standard in SSC. Alternatively, R and T could be the same person, but the notations use different letters. This is ambiguous. Hence cannot be determined.
Advanced Example 4 (Generation Gap Calculation)
A is the grandmother of B. C is the husband of A. D is the brother of B. E is the father of D. How is E related to C?
a) Son b) Father c) Brother d) Grandson
a) Son b) Father c) Brother d) Grandson
Solution: a) Son. A is grandmother of B. C is husband of A, so C is grandfather of B. D is brother of B, so D and B are siblings, both grandchildren of A and C. E is father of D, so E is the parent of D. Since D is grandchild of C, the father of D (E) must be the child of C. Therefore E is the son of C.
Advanced Example 5 (Photograph — Self Reference)
A woman pointed to a photograph and said, "His mother is the only daughter of my mother." How is the woman related to the person in the photograph?
a) Mother b) Aunt c) Grandmother d) Sister
a) Mother b) Aunt c) Grandmother d) Sister
Solution: a) Mother. "My mother" = woman's mother. "Only daughter of my mother" = the woman herself (since she is the only daughter). "His mother is..." = the woman is the mother of the person in the photograph. Therefore, the woman is the mother of the person in the photograph.
Advanced Example 6 (Spouse Chain)
P is the husband of Q. R is the sister of P. S is the wife of R. T is the brother of S. How is T related to Q?
a) Brother-in-law b) No relation c) Brother d) Cousin
a) Brother-in-law b) No relation c) Brother d) Cousin
Solution: b) No relation. P is husband of Q, so Q is wife of P. R is sister of P, so R is Q's sister-in-law (husband's sister). S is wife of R, so S is married to R. T is brother of S, so T is S's brother. T is the brother of the wife of Q's sister-in-law. T has no blood or marriage relation to Q. They are connected only through two marriages with no direct link.
Advanced Example 7 (Coded with Multiple Operators)
If 'A * B' means A is the father of B, 'A / B' means A is the mother of B, 'A + B' means A is the brother of B, 'A - B' means A is the sister of B, then what is the relation of M to P in 'M * N / O - P'?
a) Grandfather b) Great-grandfather c) Father d) Uncle
a) Grandfather b) Great-grandfather c) Father d) Uncle
Solution: a) Grandfather. M * N = M is father of N. N / O = N is mother of O. O - P = O is sister of P. So M is father of N, N is mother of O and P (since O and P are sisters). Therefore M is the maternal grandfather of P.
Advanced Example 8 (SSC Exam Style)
In a family, there are six members A, B, C, D, E, and F. A and B are a married couple. A is the mother-in-law of C. D is the only son of C. E is the sister of D. F is the father of E. How is F related to A?
a) Son b) Son-in-law c) Husband d) Brother
a) Son b) Son-in-law c) Husband d) Brother
Solution: b) Son-in-law. A and B are married. A is female (mother-in-law of C). So B is male, husband of A. A is mother-in-law of C, meaning C is married to A's child. D is only son of C. E is sister of D, so D and E are siblings, children of C. F is father of E, so F is the father of E and D. Since C is the parent of D and E, and F is also the father, F and C must be the same person? No, F is father of E, so F is the male parent of E and D. C is also parent. So C and F are the parents of D and E. So C and F are a married couple (husband and wife). But D is "only son of C" — so C is the mother (since C is female — actually C's gender is not explicitly stated but "only son of C" suggests C could be either parent). Wait: A is mother-in-law of C. Mother-in-law = wife's mother or husband's mother. So C is married to A's child. If A is female and mother-in-law of C, then C is either the husband of A's daughter or the wife of A's son. F is father of E, and E is sister of D, and D is son of C. So F is the father of C's children. Therefore F is married to C. So F is A's son-in-law (married to A's daughter) or A's son (married to C). But F is father of C's children, and A is mother-in-law of C. If C is married to A's child, and F is C's spouse, then F is A's child. So F is A's son, and C is A's daughter-in-law. So F is A's son, option a? But the answer key says son-in-law. Let me re-express: A is mother-in-law of C. So C is married to A's child. D is only son of C. E is sister of D, so E is daughter of C. F is father of E, so F is father of D and E. Therefore F and C are parents of D and E. So F is the husband of C (or C is the husband of F). Since A is mother-in-law of C, if C is female, then C married A's son. And F is C's husband, so F is A's son. But if C is male, then C married A's daughter. And F is married to C? That doesn't fit. Actually, F is father of E, and E is child of C. So F is the other parent of E. So F and C are a couple. If C is female, then F is male (father of E). A is mother-in-law of C (female), so A's child is married to C. That child would be male (since C is female). So A has a son who is married to C. But F is also married to C (as the father of E). So F would be A's son? That works. Wait, if F is A's son and married to C, then A is F's mother. And A is mother-in-law of C (since C married A's son F). So C is female, F is male, they are married. D and E are their children. So F is A's son, option a. But option is son vs son-in-law. If F is A's son, answer is a) Son. Let me check: A is mother-in-law of C. C and F are parents of D and E. F is father of E. So F is C's husband. So C is married to A's child (F). Therefore F is A's child. So F is A's son. But is F the son or son-in-law? If F is A's son, then F is A's child, not in-law. So answer is a) Son. Wait, the answer options include both "Son" and "Son-in-law". Based on the analysis, F is A's son (since A is mother-in-law of C, and C is F's wife). But there's another interpretation: A is mother-in-law of C, so C is married to A's child. F is father of C's child, so F is C's husband. Therefore F is A's son-in-law if A's child is C's wife. But if A's child is C's husband, then F is A's son. The ambiguity: is C male or female? If C is female, then A's child (male) is married to C, and F is also married to C — impossible. So C must be male, and F is C's wife? But F is "father of E" so F is male. So C is male, F is female? No, F is "father" so male. This creates a contradiction. Actually: C is parent of D and E. F is also parent (father). So F and C are the two parents. If F is male (father), then C must be female (mother). So C is female. Then A is mother-in-law of C, meaning A's child (male) is married to C. But C is married to F (since F is father of C's children). So F = A's son. Therefore F is A's son, answer a. But this means A's son F married C, and A is C's mother-in-law. That works. So answer is a) Son.