Introducing a woman a man said, “Her mother is the sister of my grandmother’s only son. How is woman related to man?

cousin sister

Note:

↑ or ↓ ⇒ Upward or downward line shown "generation gap" .

   =    ⇒ Double lines shown "relation b/w Husband & Wife"

   —   ⇒ single line shown "relation between them other than Husband & Wife".

   +   ⇒ Plus sign shown " Male".

   -   ⇒minus sign shown " Female".