Blood relations for AFCAT: draw the tree, state the gender, read the answer

Blood relation questions describe a chain of family links and ask how two people are related. "P is the brother of Q. Q is the daughter of R. How is P related to R?" Read quickly and in your head, these get muddled after the second link. Drawn on paper, almost all of them take under a minute.

This guide covers the vocabulary you need, a drawing method that works for every type, the special cases (pointing questions, coded relations and three-generation families), and the one rule that trips up more candidates than any other: never assume someone's gender from their name.

The vocabulary

Most answers are one of these words. Know them both ways: your father's brother is your uncle, and you are his nephew or niece.

In these questions, "brother" and "sister" mean full siblings with the same parents unless the question says otherwise.

The gender rule

Names do not tell you anyone's gender. Use only what the question says: words like brother, sister, son, daughter, father, mother, husband, wife, he, she, man, woman, boy and girl.

If the question gives no gender for the person you are describing, the answer must be gender-neutral (parent, child, sibling, grandparent) or "cannot be determined". Options may include both "father" and "mother" precisely to catch candidates who guess.

The method: draw as you read

1. Fix the question first. "How is A related to B?" asks what A is to B. Your answer will be a word such as "A is B's ___".
2. Draw one generation per level. Parents above children. Keep siblings on the same level, joined by a horizontal line. Join spouses with a double line or an equals sign.
3. Mark gender only when stated. Write M or F beside a letter the moment the question gives it. Leave it blank otherwise.
4. Add each fact as you read it, before reading the next.
5. Read the answer from the drawing. Count the generations between the two people, then check the gender of the first person.

Why it works: relations are built from just three links: parent–child, sibling and spouse. A tree shows every link at once, so you never have to hold a chain of five clues in memory. Counting levels tells you the generation gap, which picks out the family of the answer (uncle, grandparent, cousin), and the gender finishes it.

Worked examples

Example 1. P is the brother of Q. Q is the daughter of R. How is P related to R?

• Q is R's daughter, so Q is one level below R.
• P is Q's brother, so P is also R's child, and "brother" tells us P is male.
• P is R's son.

Example 2. X is the father of Y. Y is the mother of Z. How is X related to Z?

• X is two levels above Z, and X is male.
• The link runs through Y, Z's mother. So X is Z's maternal grandfather.

Example 3. M is the child of N. How is N related to M?

• N is one level above M, so N is M's parent.
• The question gives no gender for N. The answer is parent; "father" or "mother" cannot be determined.

Example 4 (photograph). Pointing to a photograph, a person says, "This is the only son of my father's only child." How is the person in the photograph related to the speaker?

• Decode from the inside: "my father's only child" is the speaker, because the speaker is one of their father's children and there is only one.
• "The only son of" the speaker is the speaker's son.
• The photograph shows the speaker's son. The speaker's own gender is not needed.

Example 5 (pointing). Pointing to a woman, a man says, "Her mother is the only daughter of my mother." How is the woman related to the man?

• "The only daughter of my mother": the man is male, so this is not him. It is his sister.
• The woman's mother is the man's sister.
• So the woman is his sister's daughter: his niece.

Example 6 (three generations). In a family of six, P and Q are a married couple; P is male and Q is female. R is the only son of P and Q. S is R's wife. T and U are the children of R and S. T is male and U is female. How is Q related to U, and how is S related to P?

• Draw P = Q on the top level, with P marked male and Q female, as stated.
• R, male, below them, married to S, who is female ("wife").
• T (male) and U (female) on the bottom level, below R and S.
• Q is two levels above U through U's father, so Q is U's paternal grandmother.
• S is married to P's son, so S is P's daughter-in-law.

Coded relations

Some questions replace relations with symbols. Suppose:

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

Decode one symbol at a time, from left to right, adding each link to your drawing.

Worked. What does P ÷ Q × R + S tell you about P and S?

• P ÷ Q: P is Q's mother (P is female).
• Q × R: Q is R's brother, so R is also P's child.
• R + S: R is S's father (R is male).
• P is the mother of S's father, so P is S's paternal grandmother.

Practice set

Use the symbols above (+ father, − sister, × brother, ÷ mother) for questions 6 and 7.

1. A is the sister of B. B is the son of C. How is A related to C?
2. D is the mother of E. E is the brother of F. How is D related to F?
3. G is the son of H. H is the sister of I. How is G related to I?
4. J is the father of K. K is the sister of L. L is the husband of M. How is J related to M?
5. Pointing to a boy, a woman says, "He is the son of the only son of my father." How is the boy related to the woman?
6. What does A × B ÷ C tell you about A and C?
7. If E − F + G, how is E related to G?
8. K is a parent of L. L and N are siblings. N is married to O. How is K related to O?

Answers:

1. Daughter. A is B's sister, so A is also C's child, and "sister" makes A female.
2. Mother. E and F are siblings, so D is F's mother too.
3. Nephew. G is the son of I's sister.
4. Father-in-law. J is L's father, and L is M's husband.
5. Nephew. The only son of the woman's father is her brother (she is a woman, so it is not her). The boy is her brother's son.
6. A is C's maternal uncle. A is B's brother, and B is C's mother.
7. Paternal aunt. E is F's sister, and F is G's father.
8. Parent-in-law; father or mother cannot be determined. K is N's parent too, and N is O's spouse, but K's gender is never given.

What to do next

• Redraw every example above without looking, marking gender only where the question states it.
• Practise 15 questions a day for a week, including at least five pointing questions and five coded ones.
• Move on to direction sense and seating arrangement, which use the same draw-as-you-read habit.