What is my father-in-law's sister to me?
Your father-in-law's sister is your aunt by marriage — she is your spouse's aunt, and the marriage extends the same courtesy seat to you. English has no formal single word for her, so 'aunt by marriage,' or simply 'aunt,' is what families use. No blood runs between you.
Relationship
Aunt by marriage
English has no single formal word for this relative — “aunt by marriage” is the label genealogists use.
- You
- Your father-in-law
- His sister
From the other side, you are their niece or nephew by marriage.
This connection runs through a marriage, not a shared ancestor, so the ancestor chart can't draw it.
The calculator below works out blood relationships through a shared ancestor — use it to explore the rest of your tree.
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This relationship sits outside the shared-ancestor model, so the card above carries the answer and the calculator opens in its default state. Work out any blood relationship with it, or open the full relationship calculator.
FAQs
What would my father-in-law's sister be to me?+
Your aunt by marriage — the same answer as for your spouse's aunt, because that is who she is.
Who am I to my father-in-law's sister?+
You are her niece or nephew by marriage.
Does the calculator store my family details?+
No — it runs entirely in your browser. Nothing you enter is uploaded or saved on our servers.
Start with one relative and see what comes back.
Add what you remember and AncestorIQ searches for the rest. Free to build your tree for as long as you like.
No credit card needed. Your tree stays yours.
