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Weasleys, Prewetts, and the Black Family Tree

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The Harry Potter Canon


We got some illuminating comments about my recent work on Fred and George’s page. They raised several “Weasley” issues, mainly ones having to do with Prewett and Weasley names on the Black Family Tree — so I’ve been revising all of the Weasley pages to clarify what is canon and what is guesswork.


  • Arthur was one of three brothers and had no sister. We don’t know his brothers’ names.
  • Molly’s maiden name was Prewett and she had at least 2 brothers, Gideon and Fabian. We don’t know if Molly had sisters; none are ever mentioned.
  • Ron (and by extension Bill, Charlie, Percy, Fred, George and Ginny) had an uncle Bilius, an aunt Muriel and a grandfather who played Wizard Chess. In addition to uncles Gideon and Fabian, of course.
  • Ginny is the only Weasley girl for generations.
  • Molly refers to a relative as “Our Great Auntie Muriel.”
  • Molly and Sirius are “cousins by marriage.”
    • Therefore, Molly’s parents are probably closely related to the ‘Ignatius Prewett’ listed on the Black Family tree. If the Black Family tree Jo drew is complete, Ignatius and Lucretia cannot be Molly’s parents themselves because they are indicated as being childless.
  • Arthur is “something like” Sirius’s second cousin once removed. This describes a relationship where one person’s great-great grandparent is the same person as the other person’s great grand-parent.
    • Therefore, Septimus Weasley is Arthur’s father. Septimus’s children would indeed Sirius’s second cousins once removed. Assuming the Black family tree Jo drew is complete, this relationship fits the facts and can be explained no other way.

Guesswork (not canon):

  • Edit: Auntie Muriel (HBP14, 29) is a member of the Prewett family. Not canon: We know neither Arthur nor his father had sisters, but any wife of their brothers would also be an aunt. “Auntie” can also be an honorary term. Aunt Muriel (whose goblin-made tiara Molly offers to Fleur) is probably a Prewett, but this cannot be canon without more information (thanks to ‘Reader2’ for pointing this out).
  • Bilius was one of Arthur’s 2 brothers. Not canon: We don’t know Bilius’s surname and we don’t know if Molly had more than 2 brothers. “Uncle” can also be an honorary name given to non-family members.
  • The grandfather who gave Ron the chess set is Septimus Weasley, Arthur’s father. Not canon: We don’t know his surname, so it could have been either Arthur’s father Septimus, or Molly’s father.

Thanks to Bel, John, Reader2, Marco, and Julie Stevenson for their helpful comments!


Pensieve (Comments)

  • Lee-Lee

    also, it looks like Molly shouldn’t be Ignatius and Lucretia’s daughter because that would make her Sirius’s blood first cousin (and third), rather than a cousin of sorts by marriage. As his father and and Lucretia are siblings (and his father and his siblings were his mother’s second cousins anyway)

  • Reader2

    Well, the Prewett dillema is settled now.

    Great to see that.

    I have no way to pick on the site now, but I do have a suggestion.

    JKRs site now has way more information on Mafalda, it might be fun if you add that info to your site.

    You’ve sure done a great job summing up all the Weasleys and Prewetts.

    I bet you are looking forward to Blacks, Malfoys and Lestranges. 😉

  • Nymphadorable

    I suspect that the Ignatius Prewett still is the reason that Percy’s middle name is the same. So possibly a great-uncle of Molly’s? That would also account for the relative by marriage concept.

  • Nymphadorable

    Oops — forgot to add that you’re not 100% correct about Auntie Muriel. She could still be the wife of a Weasley male. There’s not any definitive proof that she’s a blood great aunt, she could be one by marriage which would still give her the same title.

  • Lisa

    You are absolutely right about Muriel.I have downgraded assertions about her to “guesswork.”

    Auntie Muriel (HBP14, 29) is a member of the Prewett family. Not canon: We know neither Arthur nor his father had sisters, but any wife of their brothers would also be an aunt. “Auntie” can also be an honorary term. Aunt Muriel (whose goblin-made tiara Molly offers to Fleur) is probably a Prewett, but this cannot be canon without more information.

  • fernajen

    I wonder if Ignatius’s marriage to Lucretia was his second marriage. Because that would make Molly, Sirius’s cousin by marriage but not by blood.

  • Lisa

    fernajen, that would also work!

  • Pathan

    In the swedish translation the term used is in translations “old mothers sister” this term would be used for my mothers mothers sister or my mothers brothers wife which would be old mothers sister by marrige.
    In swedish the relationship name is different depending on which side the relationship is (mother sister or father sister).
    One would wonder if this things is checked by the translator or if he only make a guess?
    That become a bit messy but anyway…

  • Lisa

    Thanks, Pathan! Steve may know your translator, so I will ask him.

  • Sandra

    Hi Lisa and Pathan,
    At some Dutch Harry Potter sites, people have also been wondering whether the translators have more information than we do. (They couldn’t find out, though…)
    The Dutch translator (Wiebe Buddingh’) was interviewed just after book 4 was released, and he then said that he didn’t know more than what was written in the books. He had never spoken to Jo (might have changed, though).
    He also said that it is sometimes really hard to translate some things, because he doesn’t know what’s going to happen later on (he said he would have gone for another name for Cedric Diggory [Carlo Kannewasser] after reading book 4, he just knew more about him than after reading book 3), or sometimes he simply just didn’t know enough to be able to translate (for example, “cousin” has to be translated into either “neef” = male cousin, or “nicht” = female cousin, so you’d really need to know the gender).
    So I don’t think (though it would be very nice, because if you’d combine all the tranlations with extra information… I’d love that…) translaters know more than we do.
    But I do remember reading that Jo has once told a Portuguese translator the gender of “Blaise Zabini” who was just about to be sorted (it had something to do with the grammer of calling a boy or a girl to come forward).

  • Reader2

    I thought all the issues were settled with the Weasley family, but I just reasized one more thing.

    Do you have any proof that the accountant-cousin is a muggle and not a squib or a wizard who abandoned magic?

    On her site JKR mentions that the accountant’s wife is a muggle (that would be one more family member by the way), to me that sounds like a suggestion that the accountant himself is not a muggle.

  • beachcomber

    The comment by Ron was that there was an accountant in the family, but they didn’t talk about him. It’s never said that he is or isn’t a wizard.

  • Sandra

    But if only one member of the Prewitt and Weasley families is an accountant, and the rest of the family members are all wizards, then he must be a squib, because otherwise they can’t be related. Especially, because his wife is a muggle, so it can’t be that a witch of either of the families married a muggle who is an accountant. Or am I missing something?

  • Sandra

    Oh, and I forgot, being a squib is something wizards are ashamed of, so maybe that’s the reason why they don’t talk much about him?
    But it of course doesn’t rule out that a wizard can’t abandon the wizarding world, and become an accountant…

  • Ali

    Wasn’t there a mention about Ginny being the seventh daughter of a seventh son of a seventh son? If so, how can Arthur only have two brothers? Shouldn’t he have six? I’m confused.

  • Lisa

    Ali, you sent me on a hunt through the QQQ to clarify the situation, because I knew she mentioned this in one of the interviews. There are three sources that I am aware of on this.

    The first is the books where Ginny is clearly the 7th child in the Weasley family and the only daughter.

    The second comes from Jo’s website where she has a page in the Extra Stuff section entitled “Some Random Facts about the Weasley Family.” There she says that “Arthur Weasley was one of three brothers. Ginny (full name Ginevra, not Virginia), is the first girl to be born into the Weasley clan for several generations.”

    And third is the recent interview with Melissa and Emerson where she makes this statement: “The backstory with Ginny was, she was the first girl to arrive in the Weasley family in generations, but there’s that old tradition of the seventh daughter of a seventh daughter and a seventh son of a seventh son, so that’s why she’s the seventh, because she is a gifted witch. I think you get hints of that, because she does some pretty impressive stuff here and there, and you’ll see that again.”

    So Jo was talking there about the *tradition* of the seventh son and how she used it for Ginny as the seventh child. She really wasn’t talking about Arthur at all so this statement doesn’t contradict her website page where she says Arthur was one of 3 boys.

  • Deborah Hubbard

    If the seventh son of a seventh son is special, and so is the seventh daughter of a seventh daughter, then in these gender-free times, perhaps Molly might be the youngest of a family of numerous daughters as well as her known brothers? Then the sums would work out … although Ginny is her own witch and doesn’t need outside influences as far as I can see. She’d make it anywhere and under any circumstances.

    Could be that Fleur’s wedding guest list will clarify this – it might be a lo-o-ong one!

  • Grace has Victory

    While it is not canon, I think it is a reasonable educated guess that Ignatius Prewett is the maternal grandfather of Ron Weasley. Circumstantial evidence to support this theory includes…

    (1) Ginny’s middle name is “Molly, of course”, and Ron’s is Bilius, suggesting that all the Weasley children are middle-named after relatives. That means Ignatius is also a name that has appeared in the family before.

    (2) The most natural interpretation is that the eldest son is named after his father (“William Arthur”) and the next two after their grandfathers (presumably “Charles Septimus” and “Percy Ignatius”).

    (3) Ignatius and Lucretia have no children; this possibly means that they were married late in life, i.e. that she is his second wife.

    (4) If Lucretia Black is Molly’s stepmother, that does indeed make Molly a “cousin by marriage” (or step-cousin) of Sirius Black.

    (5) This theory suggests a very interesting family dynamic. If Molly disliked her stepmother, she may have automatically been prejudiced against the stepmother’s nephew. If she only met Sirius occasionally before OotP, that may explain their difficult relationship throughout Book V.

    On “our Great-Aunt Muriel”…

    Does this expression suggest that Muriel is the grand-aunt of both Arthur and Molly? She could be the sister of one of Molly’s grandparents, and married to the brother of one of Arthur’s. This is only a speculation, but it’s a possibility.