Blood Relations — AAI ATC Reasoning Lesson

Before you start

Learning objectives and outcomes

Blood relation questions are lost to sloppy notation, not to hard logic. This chapter fixes the notation first.

Objective 1Know every relation term the exam uses, including maternal and paternal distinctions and in-law chains.

Objective 2Draw a standard family tree with a fixed symbol set — generation by generation, never left to right.

Objective 3Decode "pointing to a photograph" statements by working backwards from the speaker.

Objective 4Solve coded-symbol chains like S × T * O – P ! V by translating one symbol at a time.

Outcome AFinish any two-generation question in under 50 seconds.

Outcome BIdentify when gender is undetermined, which is the most common trap in the answer options.

Subtopic 1

The relation vocabulary

Before the logic, the language. Exams do not say "grandmother" — they say "mother's mother", and one of the four options will say "father's mother" to catch you. Learn the two-step names cold.

Exam phrase	Plain meaning	Watch out for
Mother's mother / father's mother	Maternal / paternal grandmother	Both are "grandmother" — options split them deliberately
Mother's brother	Maternal uncle	Father's brother is a different option
Father's sister's husband	Uncle by marriage	Not a blood relation, but still asked
Brother's son / sister's son	Nephew	Both are nephew — gender of the sibling does not change it
Son's wife	Daughter-in-law	Often disguised as "wife of the only son"
Only daughter of X's mother	X herself, if X is female	The classic self-reference trap

The gender rule

Half of all wrong answers come from assuming a gender the question never gave. Names like Ravi or Priya are hints, but a letter like P or T carries no gender at all unless a relation term fixes it.

Fixed by wife, mother, sister, daughter → female
Fixed by husband, father, brother, son → male
Cousin, child, spouse, sibling → undetermined

Figure 5.1 — Relation vocabulary map A single family tree with every exam term labelled on it: maternal grandmother, paternal uncle, niece, daughter-in-law, brother-in-law. Upload image here

✈ AAI ATC relevance — appears in the General Intelligence section of every shift analysed from 2021 to 2025

Memory trick — "Maternal = mother's side"

Maternal always traces through the mother, paternal always through the father. If the question says "maternal uncle", the chain must pass through a mother somewhere. If it does not, the option is wrong.

EasyATC Pattern

How is your mother's father's only son related to you?

Mother's father is your maternal grandfather. His only son is your mother's brother — a maternal uncle. He cannot be your father, because your father is not your grandfather's son.

ModerateATC Pattern

A is the sister of B. B is the son of C. C is the mother of D. How is A related to D if D is male?

B and D are both children of C, so A, B and D are all siblings. A is stated to be a sister, so A is D's sister. The word "sister" in the first line fixes A's gender for us.

HardATC Pattern

P is the child of Q. Q is the child of R. R has only one daughter, S, who has no children. How is P related to S?

S has no children, so Q is not S — Q must be R's other child. P is therefore the child of S's sibling, making P a nephew or a niece. P's gender is never given, so the relation cannot be determined. The word "child" is deliberately gender-neutral.

Subtopic 2

Family tree notation

Every candidate who solves these quickly uses the same six symbols. Adopt them now and never invent your own mid-exam.

The standard symbol set

+ male · − female · ═ married couple (double line)
│ parent to child (vertical) · — siblings (single horizontal) · ? gender unknown

The one rule that matters: every generation gets its own horizontal row. Grandparents on top, parents in the middle, children at the bottom. The moment you let a cousin drift up a row, the question is lost.

Figure 5.2 — Three-generation tree with standard symbols Grandparents joined by a double line on row 1, their children on row 2 with vertical drops, grandchildren on row 3, each marked + or −. Upload image here

Memory trick — "Rows are generations"

If two people are on the same row they are siblings, cousins or spouses. If they are on different rows, one is an ancestor of the other. You can answer half the options just by counting rows.

Worked example — step by step

M is the father of N. N is the sister of O. O is married to P. P is the mother of Q. How is M related to Q?

Row 1: M, male, father.
Row 2: N and O are M's children, drawn side by side. N is female; O's gender is open so far.
P is married to O, so P sits beside O on row 2 joined by a double line. P is the mother of Q, so P is female — which makes O male.
Row 3: Q, child of O and P.
M is two rows above Q and connected through O, his son. Answer: M is Q's grandfather.

EasyATC Pattern

In the standard notation, what does a double horizontal line between two people mean?

A double line marks marriage, a single line marks siblings, and a vertical line marks the parent-to-child link. Keeping these three distinct is what stops a spouse being mistaken for a sibling.

ModerateATC Pattern

A ═ B are parents of C and D. C is married to E, and they have a son F. How is B related to F?

B is on row 1, F is on row 3, connected through C on row 2. That makes B a grandparent. Nothing in the question fixes whether B is the father or mother, so the precise term stays open.

HardATC Pattern

R is the son of S. S is the daughter of T. T has two children, S and U. U's daughter is V. How is V related to R?

S and U are siblings on row 2. R is S's child and V is U's child, so both sit on row 3 with different parents. Children of siblings are cousins. Same row means no aunt or niece relation is possible.

Subtopic 3

Pointing and dialogue questions

"Pointing to a photograph, a man said…" These read as puzzles but they are mechanical. The trick is to start from the person in the photo and walk backwards to the speaker, not forwards.

The backwards method

Call the person in the photograph X and put them on the page first.
Read the sentence from the end backwards, attaching one relation at a time.
The last person you reach is the speaker. Mark them clearly.
Now read off the relation the question asks for — usually speaker to X.

Reading forwards from the speaker is where people go wrong, because the sentence is written backwards on purpose.

Figure 5.3 — Working a photograph question backwards The sentence broken into fragments with arrows running right to left, and the matching tree built up beside it. Upload image here

Memory trick — "Photo first, speaker last"

Write the photographed person at the bottom of your page and build upwards. The speaker always ends up somewhere you can see, and the answer is one glance away.

EasyATC Pattern

Pointing to a photograph, a man said, "She is the daughter of my grandfather's only son." How is the woman related to him?

The grandfather's only son must be the speaker's own father. The daughter of his father is therefore his sister. "Only son" is the phrase that closes off the cousin option.

ModerateATC Pattern

Pointing to a man, a woman said, "His mother is the only daughter of my mother." How is the woman related to the man?

The only daughter of the speaker's mother is the speaker herself, since she is female. So the man's mother is the speaker — she is his mother. This self-reference is the whole point of the question.

HardATC Pattern

Pointing to a woman, a man said, "Her father's only sister is my mother's mother." How is the woman related to the man?

The man's maternal grandmother is the sister of the woman's father. So the woman's father and the man's grandmother are siblings on the same row. The woman is one row below her father, which puts her on the same row as the man's mother — she is the man's mother's cousin.

Subtopic 4 · highest yield

Coded symbol relations

This is the AAI ATC signature format. You are given a key — 'A + B' means A is the brother of B and so on — then a chain like S × T * O – P ! V, and asked how two of them are related. Both verified previous year questions in this chapter are of this type.

Read the chain strictly left to right

Each symbol connects the person immediately before it to the person immediately after it. Nothing else. Translate the whole chain into plain sentences before you draw anything.

S × T → "S is the wife of T"
T * O → "T is the father of O"
O – P → "O is the sister of P"

Only once every symbol is a sentence do you build the tree. Trying to draw and decode at the same time is how the chain gets scrambled.

Figure 5.4 — Chain decoded into a tree The symbol chain on the left, the translated sentences in the middle, and the finished three-row family tree on the right. Upload image here

Memory trick — "Translate, then draw"

Write the plain sentences in the margin first. It costs ten seconds and saves you from the single most common error, which is reversing the direction of a relation.

Worked example — the 2025 paper question

Key: A + B = A is the brother of B · A – B = A is the sister of B · A / B = A is the husband of B · A ! B = A is the mother of B · A × B = A is the wife of B · A * B = A is the father of B.
Chain: S × T * O – P ! V. How is O related to P?

S × T → S is the wife of T. So T is male and S is female.
T * O → T is the father of O. O drops one row below T and S.
O – P → O is the sister of P. This fixes O as female and puts P beside her.
P ! V → P is the mother of V, so P is female and V sits one row lower.
The question asks how O is related to P, and step 3 answers it directly. Answer: sister.

ModeratePYQ 2025 · Shift 1

In a certain code language: 'A + B' means A is the brother of B, 'A – B' means A is the sister of B, 'A / B' means A is the husband of B, 'A ! B' means A is the mother of B, 'A × B' means A is the wife of B, 'A * B' means A is the father of B. How is O related to P if S × T * O – P ! V?

The segment O – P translates directly to "O is the sister of P". The rest of the chain establishes the family around them but does not change that link. The other options are there to tempt anyone who reads the chain right to left.

HardPYQ 2021 · Shift 2

'P ÷ Q' means P is the son of Q, 'P − Q' means P is the husband of Q, 'P × Q' means P is the brother of Q, 'P + Q' means P is the wife of Q. If J ÷ H + M ÷ S – F, then how is F related to J?

J is the son of H; H is the wife of M, so M is J's father. M is the son of S, making S J's grandfather. S is the husband of F, so F is S's wife and therefore J's grandmother. Three generations, decoded one symbol at a time.

HardATC Pattern

Using the same key as the 2025 question above, how is V related to T in S × T * O – P ! V?

T is the father of O, and O is the sister of P, so P is also T's child. P is the mother of V, which puts V one row below P and two rows below T — a grandchild. Nothing in the chain fixes V's gender, so neither son nor daughter can be chosen.

Subtopic 5

Generation counting and mixed puzzles

Longer questions give you five or six people and ask how many generations the family spans, or place a blood relation inside a seating puzzle. The tree still works; you just need to be disciplined about rows.

Counting generations

Generations = number of occupied rows
Same row → siblings, cousins or spouses
Rows apart = n → n-times removed ancestor or descendant

A married-in spouse never adds a generation. A common error is to place a son-in-law one row below his wife, which silently invents a fourth generation that does not exist.

Figure 5.5 — Counting generations correctly A four-row family with spouses drawn beside their partners rather than below, and the generation count marked on the left margin. Upload image here

Memory trick — "Spouses sit, children drop"

A spouse joins the row you are already on. Only a child moves you down a row. Repeat that once before every long question and generation counts stop going wrong.

EasyATC Pattern

A family has A and his wife B, their sons C and D, and C's daughter E. How many generations does this family span?

Row 1 holds A and B, row 2 holds C and D, row 3 holds E. B is a spouse and so shares A's row rather than adding one. Three occupied rows means three generations.

ModerateATC Pattern

In a family of six, there are two married couples. K is the grandmother of L and mother of M. N is the wife of M and mother of L. How is L related to K's husband?

K and her husband are on row 1. M and his wife N are on row 2. L is the child of M and N on row 3. Two rows below K's husband makes L his grandchild, and no gender is given for L so the term stays general.

HardATC Pattern

P is the brother of Q. Q is the mother of R. R is married to S. T is the father of S. How many generations are there among P, Q, R, S and T?

P and Q are siblings, so they share a row. T is the father of S, which places T one row above S — the same row as P and Q. R is Q's child and S is R's spouse, so both sit on the row below. Two occupied rows means two generations. Five named people does not mean five generations, which is exactly what option 4 is testing.

Exam strategy

Six tips that hold in the AAI ATC hall

Always drawEven a two-line question. Twenty seconds of tree beats a minute of head-scratching.

Translate coded chains firstPlain sentences in the margin, then the tree. Never both at once.

Mark gender the instant it is fixedA + or − beside each letter as soon as a relation term reveals it.

Trust "only son" and "only daughter"These phrases exist to close off an option. They are never decoration.

Check for undetermined genderIf nothing fixes it, "cannot be determined" is often the intended answer.

Spouses share a rowMarrying in never creates a new generation.

Quick revision

Chapter summary sheet

Symbols+ male · − female · ═ married · │ parent-child · — siblings · ? unknown

Golden ruleOne row per generation, always.

Maternal vs paternalMaternal traces through the mother, paternal through the father.

Nephew / nieceChild of a brother or a sister — the sibling's gender is irrelevant.

Photograph questionsStart from the person in the photo and read backwards to the speaker.

"Only daughter of my mother"Is the female speaker herself.

Coded chainsEach symbol links only the two names touching it. Left to right, one at a time.

Gender-neutral trapsChild, cousin, spouse and sibling never reveal gender.

Generation countEquals the number of occupied rows. Spouses do not add rows.

↓ Free download — Blood Relations question PDF

Four pages of practice covering every question type in this chapter, with blank titled boxes left for you to draw the family trees by hand. Print it, solve it, keep it.

Download the free PDF Join our live classes — extremely affordable

End of chapter

Comprehensive assessment

Nine question formats, building in difficulty. Full solutions are in the downloadable PDF above.

A · Multiple choice questions

1. How is your father's mother's only daughter-in-law related to you?

2. A is the son of B. C is the sister of A. D is married to C. How is D related to B?

3. Pointing to a boy, a woman said, "He is the son of my mother's only son." How is she related to him?

4. Which of these relation terms never reveals gender?

5. P's father's sister's husband is Q. How is Q related to P?

B · Assertion and reason

6. Assertion: A brother's son and a sister's son are both nephews. Reason: The gender of the sibling does not affect the term used for their child.

7. Assertion: A son-in-law belongs to the same generation row as his wife. Reason: Marrying into a family never adds a generation.

C · Match the following

Column I — description	Column II — relation
(a) Mother's brother	(i) Nephew
(b) Father's father	(ii) Maternal uncle
(c) Sister's son	(iii) Daughter-in-law
(d) Son's wife	(iv) Paternal grandfather

D · Fill in the blanks

8. In standard notation, a double horizontal line represents .

9. The number of generations in a family equals the number of .

10. "The only daughter of my mother", spoken by a woman, refers to .

11. A relation traced through the mother's side is called .

E · True or false

12. A cousin's gender can always be determined from the word "cousin".

13. A spouse occupies the same generation row as their partner.

14. In a coded chain, a symbol may connect two people who are not adjacent to it.

15. Photograph questions are best solved by starting from the speaker.

F · Short answer

16. List the six standard family tree symbols and state what each represents.

17. Explain why "spouses sit, children drop" prevents generation-counting errors.

18. Give two relation terms whose gender is fixed and two whose gender is not.

G · Long answer

19. Set out the full four-step backwards method for photograph questions, then apply it to: "Pointing to a lady, a man said, 'Her mother's only son is my father's only son.'"

20. Explain the translate-then-draw method for coded chains and apply it to a five-symbol chain of your own construction, showing every intermediate sentence.

H · HOTS — higher order thinking

21. A chain gives you six people and four relations, and two different family trees satisfy all of them. Construct such a case and explain what extra piece of information would make the answer unique.

22. Design a coded-symbol question in which the correct answer is "cannot be determined", and justify why no option fixes the gender.

I · Previous year exam style

23. Key: 'A + B' = brother, 'A – B' = sister, 'A / B' = husband, 'A ! B' = mother, 'A × B' = wife, 'A * B' = father. How is O related to P if S × T * O – P ! V? PYQ 2025 · Shift 1

24. 'P ÷ Q' = son, 'P − Q' = husband, 'P × Q' = brother, 'P + Q' = wife. If J ÷ H + M ÷ S – F, how is F related to J? PYQ 2021 · Shift 2

25. Using the 2025 key, how is S related to V in the same chain? ATC Pattern

J · Mixed revision test

26–35. Ten mixed questions across all five subtopics, timed at eight minutes total. Full set with answer key is in the free PDF.

Learning objectives and outcomes

The relation vocabulary

The gender rule

Family tree notation

The standard symbol set

Pointing and dialogue questions

The backwards method

Coded symbol relations

Read the chain strictly left to right

Generation counting and mixed puzzles

Counting generations

Six tips that hold in the AAI ATC hall

Chapter summary sheet

↓ Free download — Blood Relations question PDF

Comprehensive assessment

A · Multiple choice questions

B · Assertion and reason

C · Match the following

D · Fill in the blanks

E · True or false

F · Short answer

G · Long answer

H · HOTS — higher order thinking

I · Previous year exam style

J · Mixed revision test

Two marks here. Thirteen more reasoning topics waiting.