Mental Ability: Blood Relations — Techniques and Practice Problems

Blood Relations is a core topic in Kerala PSC Mental Ability/Reasoning sections. Typically 2-3 questions appear in Graduate Level exams. This note covers all relationship terms, solving techniques, and practice problems.

Key Relationship Terms

Basic Relationships

Relationship	Meaning
Father’s/Mother’s father	Grandfather
Father’s/Mother’s mother	Grandmother
Father’s brother	Uncle (Paternal uncle)
Mother’s brother	Uncle (Maternal uncle)
Father’s sister	Aunt (Paternal aunt)
Mother’s sister	Aunt (Maternal aunt)
Brother’s/Sister’s son	Nephew
Brother’s/Sister’s daughter	Niece
Uncle’s/Aunt’s son/daughter	Cousin
Son’s wife	Daughter-in-law
Daughter’s husband	Son-in-law
Husband’s/Wife’s father	Father-in-law
Husband’s/Wife’s mother	Mother-in-law
Husband’s brother	Brother-in-law
Wife’s sister	Sister-in-law

Generation Markers

Term	Generations Away
Father/Mother	1 generation up
Grandfather/Grandmother	2 generations up
Son/Daughter	1 generation down
Grandson/Granddaughter	2 generations down
Brother/Sister/Cousin	Same generation
Uncle/Aunt	1 generation up (sibling of parent)
Nephew/Niece	1 generation down (child of sibling)

Solving Technique: The Family Tree Method

Step 1: Use symbols consistently:

• Male: + (plus sign)
• Female: - (minus sign)
• Marriage: = (equals between couple)
• Parent-Child: vertical line downward
• Siblings: horizontal line connecting them

Step 2: Read the statement carefully, identify each person and their gender.

Step 3: Build the tree from the information given, one relationship at a time.

Step 4: Trace the path from person X to person Y to find the relationship.

Standard Notation for Diagrams

When solving on paper:

• Draw males on the left, females on the right (or use +/- symbols)
• Place elder generation above
• Draw horizontal line between siblings
• Draw vertical line from parent to child
• Draw double line (or =) between married couple

Common Coded Language in PSC Questions

PSC questions often use phrases instead of direct relationship names:

Phrase Used in Question	Actual Meaning
”A’s father’s only son”	A himself (if only child) or A’s brother
”A’s mother’s husband”	A’s father
”A’s father’s wife”	A’s mother
”A’s brother’s father”	A’s own father
”A’s only brother’s wife”	A’s sister-in-law
”A’s father’s only daughter”	A herself (if A is female and only daughter) or A’s sister
”A’s grandfather’s only son”	A’s father (if grandfather had only one son)
“A’s mother’s only daughter’s son”	A’s son (if A is the only daughter)
“Only child of A’s parents”	A himself/herself
”Father’s father’s only son’s wife”	A’s grandmother (paternal) if grandfather had only one son

Key Shortcuts

Shortcut	Rule
”Only” is crucial	”Father’s only son” = the person themselves; “Mother’s only daughter” = herself
Count generations	Each “father/mother” = go up one; each “son/daughter” = go down one
In-law detection	If marriage is mentioned, track in-law relationships
Gender from context	”He/She/His/Her” tells gender; “Husband/Wife” tells gender; names may hint (not always reliable in exams)
Sibling detection	”A and B have the same parents” = siblings; “A’s father is B’s father” = siblings

Practice Problems with Solutions

Problem 1

Q: Pointing to a photograph, Ramesh said, “He is the son of the only daughter of the father of my brother.” How is the person in the photograph related to Ramesh?

Solution:

• My brother’s father = my father
• My father’s only daughter = my sister (or myself if female, but Ramesh is male, so = Ramesh’s sister)
• Son of my sister = my nephew

Answer: Nephew

Problem 2

Q: If A is the brother of B, B is the sister of C, and C is the father of D, how is D related to A?

Solution:

• A is brother of B (A = male)
• B is sister of C (B = female, sibling of C)
• So A, B, C are all siblings
• C is father of D (C = male)
• A is uncle (brother of D’s father)
• D is nephew/niece of A

Answer: D is A’s nephew or niece

Problem 3

Q: Introducing a man, a woman said, “His wife is the only daughter of my mother.” How is the man related to the woman?

Solution:

• “Only daughter of my mother” = the woman herself
• “His wife” = the woman herself
• So the man is her husband

Answer: Husband

Problem 4

Q: A is the father of B. But B is not the son of A. How is B related to A?

Solution:

• A is father of B, but B is not A’s son
• B must be A’s daughter (female child)

Answer: B is A’s daughter

Problem 5

Q: Looking at a portrait, a man said, “The person in the portrait is the son of my mother’s only daughter.” How is the person in the portrait related to the man?

Solution:

• Mother’s only daughter = the man’s sister (man is male, so “only daughter” is his sister)
• Wait — or if the man has no sisters, “mother’s only daughter” has no solution unless the man is wrong
• Actually: “Mother’s only daughter” = If the speaker (man) is male, mother may have only one daughter, who is man’s sister
• Son of that daughter = man’s nephew

Answer: Nephew

Problem 6

Q: If Kamal says “Ravi’s mother is the only daughter of my mother,” how is Kamal related to Ravi?

Solution:

• “Only daughter of my (Kamal’s) mother” = Kamal’s sister (if Kamal is male) or Kamal herself (if female)
• Kamal is a name commonly used for males in PSC questions
• Ravi’s mother = Kamal’s sister
• So Kamal is Ravi’s maternal uncle

Answer: Maternal Uncle (Mama)

Problem 7

Q: A + B means A is the father of B. A - B means A is the wife of B. A x B means A is the brother of B. If P + Q - R, what is R’s relationship to P?

Solution:

• P + Q: P is father of Q
• Q - R: Q is wife of R
• So Q is female, R is male, Q and R are married
• P is Q’s father, so P is R’s father-in-law

Answer: R is the son-in-law of P

Problem 8

Q: In a family of six persons — A, B, C, D, E, F — there are two married couples. B is the mother of D and E. A is the son of F. C is the husband of B. E is the granddaughter of F. How is A related to D?

Solution:

• B is mother of D and E; C is husband of B. So C and B are married.
• E is granddaughter of F, and B is E’s mother, so F is the parent/in-law of B or C.
• A is son of F.
• Since C is husband of B, and F is grandparent of E (through B), F must be C’s parent or B’s parent.
• If F is C’s mother/father: A is son of F = A is C’s sibling (brother/sister).
• Then A is uncle/aunt of D.
• Since A is “son” of F, A is male = uncle of D.

Answer: A is the uncle of D

Problem 9

Q: Pointing to a lady, a man said, “The son of her only brother is the brother of my wife.” How is the lady related to the man?

Solution:

• Lady’s only brother’s son = man’s wife’s brother
• Lady’s nephew = man’s brother-in-law
• So the lady’s brother = father of man’s brother-in-law = man’s father-in-law
• Therefore the lady is the sister of man’s father-in-law

Answer: Sister of his father-in-law (husband’s paternal aunt or wife’s paternal aunt)

Problem 10

Q: A is the son of C. C is the daughter of B. How is A related to B?

Solution:

• C is daughter of B (C = female, B = parent)
• A is son of C
• So A is B’s grandson (daughter’s son)

Answer: A is B’s grandson

Problem 11

Q: If Mohan says “This girl is the wife of the grandson of my mother,” who is the girl to Mohan?

Solution:

• Mohan’s mother’s grandson = Mohan’s son (or nephew)
• Wife of Mohan’s son = Mohan’s daughter-in-law
• Wife of Mohan’s nephew = cannot be simply determined
• Most likely intended: Mohan’s mother’s grandson through Mohan = Mohan’s son
• Girl = wife of Mohan’s son = daughter-in-law

Answer: Daughter-in-law (or nephew’s wife)

Problem 12

Q: A woman introduces a man as “the son of my mother’s only son.” How is the man related to the woman?

Solution:

• Woman’s mother’s only son = woman’s brother
• Son of woman’s brother = woman’s nephew

Answer: Nephew

Problem 13

Q: If P $ Q means P is the mother of Q; P # Q means P is the father of Q; P * Q means P is the sister of Q. What does A # B $ C * D mean?

Solution:

• A # B: A is father of B
• B $ C: B is mother of C
• C * D: C is sister of D
• So A is father of B (female, since she is mother); B is mother of C and D; A is grandfather of C and D
• D is grandchild of A

Answer: A is the grandfather of D (and C)

Problem 14

Q: Deepak said to Nitin, “That boy playing football is the younger of the two brothers of the daughter of my father’s wife.” How is the boy related to Deepak?

Solution:

• Deepak’s father’s wife = Deepak’s mother
• Daughter of Deepak’s mother = Deepak’s sister
• Two brothers of that daughter = Deepak and another brother
• The boy playing = the younger brother = Deepak’s brother

Answer: Brother

Problem 15

Q: If Rani says “Suresh’s mother is the only daughter of my mother,” how is Rani related to Suresh?

Solution:

• Only daughter of Rani’s mother = Rani herself (since Rani is female)
• Suresh’s mother = Rani
• So Rani is Suresh’s mother

Answer: Mother

Problem 16

Q: A and B are brothers. C is B’s father. D is C’s brother. E is D’s father. How is B related to E?

Solution:

• B’s father = C
• C’s brother = D
• D’s father = E
• So E is C’s father too (C and D are brothers, sharing father E)
• E is B’s grandfather

Answer: B is E’s grandson

Problem 17

Q: Pointing to a person, Anu said, “He is the brother of my uncle’s daughter.” How is the person related to Anu?

Solution:

• Anu’s uncle’s daughter = Anu’s cousin (female)
• Brother of that cousin = Anu’s cousin (male)
• So the person is Anu’s cousin

Answer: Cousin

Problem 18

Q: M is the son of P. Q is the granddaughter of O who is the husband of P. How is M related to Q?

Solution:

• O is husband of P. So O and P are married.
• M is son of P. So M is child of O and P.
• Q is granddaughter of O. So Q is daughter of one of O’s children.
• Q could be daughter of M (then M is Q’s father) or daughter of M’s sibling.
• Most likely: Q is M’s daughter or M’s niece.
• Given limited info, most PSC answers assume: M is Q’s father or uncle.

Answer: Father (most probable) or Uncle

Problem 19

Q: If MOTHER is coded as NPUIFS (each letter +1), and FATHER is coded as GBUIFS, how would SISTER be coded?

Solution:

• M+1=N, O+1=P, T+1=U, H+1=I, E+1=F, R+1=S. MOTHER = NPUIFS (confirmed)
• S+1=T, I+1=J, S+1=T, T+1=U, E+1=F, R+1=S

Answer: TJTUFS

Problem 20

Q: In a family, there are six members — A, B, C, D, E, F. A and B are married couple. A is male. C is the son of A. D is the daughter of B. E is the brother of C. F is the maternal uncle of D. How is F related to A?

Solution:

• A (male) married to B (female)
• C = son of A (and B)
• D = daughter of B (and A)
• E = brother of C; so E is also son of A and B
• Children: C (male), D (female), E (male)
• F = maternal uncle of D = brother of D’s mother = brother of B
• So F is B’s brother = A’s brother-in-law

Answer: F is A’s brother-in-law

Tips for PSC Blood Relation Questions

Tip	Explanation
Always draw	Even for simple questions, draw a small family tree
Identify gender first	He/she/wife/husband/son/daughter give clear gender clues
Watch for “only"	"Only son/daughter” is a crucial constraint
Eliminate options	In MCQ, eliminate impossible relationships first
Count generations	Up = parent/grandparent, Down = child/grandchild, Same = sibling/cousin
In-laws need marriage link	If no marriage is mentioned, it cannot be an in-law relationship