Blood Relations

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Blood Relations — Quick Facts

Key Terminology:

• Father’s son = brother or “myself” (if male speaking)
• Mother’s daughter = sister or “myself” (if female speaking)
• Brother’s sister = sister (not necessarily “me”)
• Sister’s brother = brother
• Maternal = mother’s side (related through mother)
• Paternal = father’s side (related through father)

Generation Mapping:

• Your parent’s sibling = your aunt/uncle
• Your grandparent = parent’s parent
• Your sibling’s child = your niece/nephew
• Your sibling = brother or sister (share at least one parent)

Common Relationship Phrases:

Phrase	Meaning
”Only son of father”	There are no other sons
”Married to”	Spouse relation
”Only child”	No siblings at all
”Grandmother’s only child”	One parent (either mother or father)
“Second daughter”	Two daughters total, this is the second

⚡ CAT Exam Tip: Draw a family tree diagram. Start with the subject, draw their generation, then parents, then siblings’ families. This visual approach prevents confusion in complex blood relation problems.

---

🟡 Standard — Regular Study (2d–2mo)

For students who want genuine understanding.

Blood Relations — Study Guide

Interpreting Relationship Puzzles:

Example: “A is the brother of B. B is the sister of C. C is the father of D. How is A related to D?”

Step-by-step:

1. A and B are siblings (brother-sister pair)
2. B is sister of C → C is sibling of B, so C is also sibling of A
3. C is father of D
4. Since A and C are siblings, A is D’s… uncle or aunt

Since A and C could be male or female, and we know B is female (sister), A could be male (uncle) or female (aunt). But in most puzzles, “brother” implies male, so A is uncle.

Example: “Pointing to a man, a woman said, ‘His mother is the only daughter of my mother.’ How is the woman related to the man?”

Key: “Only daughter of my mother” = the woman herself (she is the only daughter)

So the woman’s mother is the man’s grandmother (the woman is the man’s mother)

Wait, let me trace this:

• Woman’s mother = man’s grandmother
• Woman’s mother = only daughter of woman’s mother
• This means the woman is the only daughter of her own mother… unless there are sons

Actually, the phrase “His mother is the only daughter of my mother” means:

• The man’s mother = the only daughter of the woman’s mother
• Only daughter = one and only daughter

If the woman’s mother has only one daughter, that daughter is the woman. So the woman’s mother = the woman’s grandmother (through which the relation flows).

Let me re-read: “His mother is the only daughter of my mother”

• “His mother” = the only daughter of “my mother”
• The only daughter of “my mother” is “me” (the woman)
• So “his mother” = me
• Therefore the woman is the mother of the man

Answer: The woman is the man’s mother.

Coded Blood Relations:

In some CAT questions, relationships are coded:

• A + B means A is B’s sister
• A − B means A is B’s brother
• A × B means A is B’s mother
• A ÷ B means A is B’s father

Example: If P + Q means “P is Q’s sister” and Q is the son of R, and P + R means P is R’s daughter, what is R to Q?

• Q is son of R → R is Q’s father or mother
• P is Q’s sister and P is R’s daughter

If P is Q’s sister and both are children of R, then R is parent of both. Since Q is male, R could be father or mother. But in coded questions without gender specification, R is simply Q’s parent.

⚡ Common Student Mistake: Misinterpreting “only” — “only son of X” means there is exactly one male child, not “the sole surviving child.”

---

🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Blood Relations — Comprehensive Notes

Complex Family Tree Analysis:

Example Problem:

“A is married to B. B is the mother of C. C is married to D. D is the father of E. F is the son of C. G is the grandmother of F. G is married to H. H is the father of I. I is the sibling of F. J is the son of I.”

Find: (a) How is A related to F? (b) Who is J’s uncle?

Solution:

Step 1: Draw family tree from information:

        G (grandmother of F) ── married to ── H
        │                                            │
     (parent of B)                              (parent of I)
        │                                            │
        B (mother of C) ── married to ── A           I
        │                                                      │
     (parent of C)                                       │
        │                                              Sibling of F
        C ── married to ── D                                    │
        │                                                      J
     (parent of F)                                             │
        │                                                      (son of I)
        F                                                      
        (son of C)
        (sibling of I)

Actually, let me re-read: G is grandmother of F.

• If G is grandmother of F, then G’s child is F’s parent.
• B is the mother of C, and G is grandmother of F where F is son of C.
• So C is F’s parent. If F’s grandmother is G, then G is either mother of C’s father or mother of C’s mother.

But G is married to H, and I is sibling of F. So G and H are parents of either C or C’s spouse.

Let’s be systematic:

1. B is mother of C
2. A is married to B → A is B’s husband, so A is father of C
3. C is married to D → D is C’s spouse
4. D is father of E → D is father (so E is child of C and D)
5. F is son of C → C is F’s parent
6. G is grandmother of F → G is parent of either C’s mother or C’s father
7. Since B is mother of C, G could be B’s mother
8. G is married to H
9. H is father of I
10. I is sibling of F → I is also child of C (F and I are siblings)
11. J is son of I

So family tree:

• A and B are parents of C (father and mother)
• C is married to D
• C and D have children: F and I (siblings)
• G is B’s mother (since G is grandmother of F, and B is C’s mother)
• G is married to H
• H is father of I

Wait — H is father of I, but I is child of C. This means H must be C’s father (step-father) or…

Actually: H is father of I. I is sibling of F. F is son of C. So I is also child of C. Therefore H must be the father of C (and thus parent of C along with B). Since G is married to H, and G is grandmother of F (child of C), G is B’s mother (since B is C’s mother).

So: G = B’s mother = C’s grandmother = F’s great-grandmother… no, grandmother.

Summary:

• G and H are grandparents of C (and parents of B)
• B is mother of C, A is father of C
• C is parent of F and I
• D is spouse of C, parent of E
• J is child of I

Answers: (a) A is grandfather of F (A is father of C, C is parent of F) (b) J’s uncle = any brother of I’s parent… I’s parent is C. C’s sibling? None mentioned. But wait — is there another sibling of C?

Actually, looking again: F and I are siblings, children of C. J is son of I. J’s uncle would be F (father’s/mother’s brother), or another sibling of I’s parent (C).

If F and I share the same parents (C and D), then F is uncle of J (since F is I’s brother, J is I’s son). So F is J’s uncle.

JAMB Pattern Analysis (CAT 2015-2024):

• 2015: Direct relationship identification
• 2017: Multi-generation family tree
• 2019: Coded relationship symbols
• 2021: “Only” and “married to” combinations
• 2023: Complex multi-step relationships
• 2024: Family with multiple siblings and in-laws

⚡ Exam Strategy: In complex problems, assign generation levels (G1 = oldest, G2 = parents, G3 = siblings, G4 = children). Work from known relationships downward, labeling each person as you go. If a relationship cannot be determined (e.g., male or female not specified), note the ambiguity.