I have been told by native speakers that "a brother/sister of mine" is almost never used except in poems or old literature and should therefore always be "one of my brothers/sisters". Is it a valid opinion?

I have found a few example, though.

1) A sister of mine had a ‘big’ birthday last week and I wanted to make a special card for her > Fancy Fold Card with Bouquet Blooms ( Annette Sullivan: Independent Stampin' Up!® Demonstrator, Australia – )

2) Can a sister of mine, who is a lawyer, go to jail for filing a false police report about me in March of 2019? > https://www.avvo.com/legal-answers/can-a-sister-of-mine--who-is-a-lawyer--go-to-jail--4442448.html > (Highland Park, IL)> >

3) a sister of mine came down with polio > https://www.parliament.wa.gov.au/Ha...3D6351C7D048256602000FB1A7/$file/C1125008.PDF > (australia)

What do you think of it?

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    As an only child I don't have occasion to say such a thing, but my feeling is that 'a sister of mine' is more anonymous. You might say it when speaking to people who don't know your sister and don't need to; you are just using her as an example. 'My sister' feels more personal. Jun 4, 2020 at 7:54
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    but the question is "what's the difference between "a sister of mine" and "one of my sisters"?
    – user1425
    Jun 4, 2020 at 10:01
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    The same applies to 'one of my sisters', if you have several, as to 'my sister'. Jun 4, 2020 at 13:26
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    Two ways to say it. There’s really no difference.
    – Jim
    Jul 4, 2020 at 6:32
  • GoogleNgrams seem to show that your informants were perhaps too ... Nov 1, 2020 at 17:27

3 Answers 3


A “something” of mine usually means it is one of many, and it doesn’t matter much which one. “A friend of mine had his bicycle stolen”, “a teacher of mine came to school wearing non-matching sox”.

My “something” is much more specific. Like “my maths teacher”. It is unusual to say “a sister of mine” unless you have at least eight sisters.


It has the feel of active versus passive voice.

"My sister" or "One of my sisters" is more direct and therefore stronger.

  • Hello, gorlux. I think you make a valid point, but without supporting evidence, this has 'comment' status. Nov 1, 2020 at 17:32
  • I don't agree with this. The "of mine" choice, if anything, emphasizes the "mine" part. Compare "my child will not attend" and "no child of mine will attend."
    – Casey
    Dec 27, 2021 at 19:19

Perhaps we can consult Ngram


It seems "one of my brothers" is the common expression; "a brother of mine" is used, but it is unusual.

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