Molly's uncle?

Sirius tells Harry that he and Molly are "cousins by marriage" in chapter six of Order of the Phoenix. I think we can infer from this statement that Ignatius Prewett was the brother of Mr. Prewett, and thus the blood uncle of Gideon, Fabian, and Molly. Would anyone object to editing articles on members of the Prewett family to reflect this conclusion? Starstuff (Owl me!) 05:53, 17 January 2009 (UTC)

I don't think that would make them cousins by marriage, though. Ignatius is only Sirius's uncle by marriage, but his (Ignatius's) siblings wouldn't be Sirius's uncles/aunts as well. "Cousin by marriage" implies that the person is married to your cousin, doesn't it? I'm not sure, because I know it's been said, for example, that Hermione is not Harry's sister-in-law by virtue of the fact that she isn't married to his brother or the sister of his wife. However, some definitions of sister-in-law include the wife of the brother of one's spouse. This would be a similar case, but with cousins. In any case, Ignatius can't be Molly, Gideon, and Fabian's father, since that would make her a first cousin of Sirius's by blood.
However, I think Sirius may have been referring to Molly's marriage to Arthur, whose mother was a Black. Arthur is Sirius's second cousin once removed, and since Molly is married to him, it makes her and Sirius cousins by marriage. Oread 06:05, 17 January 2009 (UTC)
Sirius' statements to Harry in OotP6 make it clear that his relationship to Molly was distinct from his relationship to Arthur:
"The pure-blood families are all interrelated,' said Sirius. 'If you're only going to let your sons and daughters marry pure-bloods your choice is very limited; there are hardly any of us left. Molly and I are cousins by marriage and Arthur's something like my second cousin once removed."
If Molly's only relationship to Sirius was that she was married to his second cousin once removed, Arthur, Sirius probably wouldn't have mentioned her at all, or would've spoken of her relationship to him in terms of his relationship to Arthur.
If Ignatius was the brother of Molly's father, Mr. Prewett, then Sirius' blood aunt Lucretia would've been married to Molly's blood uncle Ignatius. Ignatius would've been uncle to both Sirius and Molly — by blood to Molly, and by marriage to Sirius. I suppose Sirius and Molly could be considered cousins of a sort through sharing an uncle.
I think JKR may have written OotP6 before she fully drew up the Black family tree. If that's the case, she would have had to try to fit all the people mentioned in that chapter into Sirius' family tree after the fact, which no doubt would've been difficult. She got it right with Arthur: he is indeed Sirius Black's second cousin once removed if he is the son of Cedrella Black.[1] But perhaps she had trouble working out how to make Molly and Sirius "cousins by marriage." However, I think it's evident from the placement of both a Prewett and a Weasley on the Black family tree that she was trying to answer the questions created by Sirius' statements to Harry. Starstuff (Owl me!) 11:35, 17 January 2009 (UTC)
I think it's a reasonable assumption you've made about Sirius's mention of Molly indicating that they are related in a way besides through Arthur. Considering that Ignatius Prewett can't be Molly's father and your observation about J.K. Rowling's inclusion of a Prewett in the Black family tree, I also agree that it seems most likely that Ignatius was an uncle of Molly and her brothers.
However, if this is the case, then Rowling has made a mistake in her understanding of consanguinity and kinship. "Cousin by marriage" means someone who is married to your cousin (one literary example I can think of is in Romeo and Juliet, in which Romeo refers to Tybalt as "cousin" after marrying Juliet, who is Tybalt's first cousin). A cousin of your cousin -- i.e. your cousin is related to x person on the other side of the family -- is not your cousin, by marriage or by anything. For instance, if Draco Malfoy has a cousin on Lucius's side of the family, this person would not be a cousin, by marriage or otherwise, of Nymphadora Tonks. But Draco's wife would be Tonks's cousin by marriage, and Remus Lupin would be Draco's cousin by marriage. People only become your relatives by marriage if they marry a blood relative, not if they are related by blood to a relative by marriage.
But, overall, I think we do have enough information to assume that Ignatius is Molly's uncle, since if he was a more distant relative, it makes even less sense for Sirius to describe her as a cousin by marriage. Oread 16:01, 17 January 2009 (UTC)
Should we add Ignatius to relevant Prewett family infoboxes with an explanatory footnote? Starstuff (Owl me!) 14:01, 24 January 2009 (UTC)
I think we should. Maybe the footnote should simply cite this page, since it's a rather long and complex explanation? Oread 21:16, 24 January 2009 (UTC)
I've updated family infoboxes and the Prewett family page, with an explanatory footnote and link back to this discussion. Oread 19:32, 26 January 2009 (UTC)

I believe it is more likely that Ignatius is Molly's father, but Lucretia isn't her mother. If Ignatius' first wife, mother of Molly, Gideon & Fabian, died and Ignatius remarried, it would make Molly and Sirius cousins by marriage. This also fits with the Weasley onomastics (naming patterns) with Percy's middle name of Ignatius. I think it is safe to assume Ignatius and Lucretia did not have any issue, as there is no indication on the tree. Maybe we should just ask Jo.......... ( 01:16, 25 March 2009 (UTC))

If Ignatius was Molly, Gideon, and Fabian's father, but Lucretia was their stepmother, that would make Sirius their step-cousin. I don't think that "cousin by marriage" is the same thing; it would be like calling your stepbrother your "brother by marriage". I tend to think it means cousin-in-law. Furthermore, Ignatius being their uncle fits in with the Weasley family naming patterns just as well. Ron's middle name is Bilius, after an uncle, thus it's easily possible that Percy was also given the name of an uncle for his middle name.
Somewhat off on a we know if divorce occurs in the wizarding world? Oread (talk) 01:35, 25 March 2009 (UTC)

Presumably divorce is possible, seeing as the wizarding world seems to be quite similar to ours in most ways, apart from in technology - I've also noticed no religion seems to come up in the books, even weddings and funerals are not religious, and it's mostly religions that oppose divorce.l-- 05:24, 2 August 2009 (UTC)Rowena.

Still, is 'step-brother' not the same as 'brother by marriage'? After all, there would be no relationship at all (in terms of immediate family) of the marriage of the respective parents hadn't taken place...

Even if that did make any sense, and I don't think it does, would JKR go through all that to make it that complicated? She probably picked the most likely scenario for the most likely definition of the word. Otherwise, she would have (or rather made Sirius have) elaborated further. So, unlikely, but I guess possible, though not plausible. 20:20, April 10, 2010 (UTC)
She may have... To clarify on the point above: if two people are married and they both have children from prior marriages or relationships, then those children become step-siblings which seems to me to mean 'siblings by marriage' in the sense of their parents' marriage, not that of their other siblings (i.e. in-laws). Before the marriage of the parents, the 'step-siblings' had no familial relationship at all. Also, we do not know what sort of naming conventions magical folk had; whether they considered such relationships to be 'step'-ones or 'by marriage' (which seems a bit more archaic a term, befitting the wizarding community). ( 02:01, November 15, 2011 (UTC))

1. Ignatius Prewett is married to Lucretia Prewett (née Black), which makes him Sirius' uncle-in-law (or, uncle by marriage).

2. Lucretia is, presumably, Ignatius' only wife, because no other marriage is mentioned, and would be a rather confusing descision for J.K. Rowling to make.

3. Lucretia can't be Molly's mother, because she is Sirius' auntie by blood, and therefore that would make Sirius and Molly cousins (by blood)

4. IF Ignatius is Molly's uncle, that would make sense, because he would be uncle by blood to Molly, and uncle-in-law to Sirius... this would result in them being cousins-in-law (i.e. 'by marriage')

I'm pretty sure Ignatius was Molly Weasley's uncle... I can't make the term 'cousins by marriage' make sense in any other situation.

~~J. Skye~~

I disagree with point 2. The family tree Jo drew was that of the Black family.Ignatius' only connection to it was his marriage to Lucretia, which resulted in no issue. Any prior marriage of his would not be depicted on the tree as it does not concern the Black family overall. Any one of the spouses of Blacks could have had previous or succeeding marriages without them being shown on the tree. ( 02:01, November 15, 2011 (UTC))
I know it's probably been decided already, but this is the actual relationship between Sirius and Molly is second cousins. I used a line from the wizard of Oz to show this: "Uncle Bill Hugson married your Uncle Henry's wife's sister; so we must be second cousins". This, too applies to Sirius and Molly; Sirius's Aunt Lucretia married Molly's aunt's husband" so they are second cousins (if the person who wrote the Wizard of Oz is correct; if they're not, then please, correct me.)HarryPotterRules1 (talk) 02:13, August 29, 2012 (UTC)

Can we shrink this down now? Pottermore mentions that Ignatius is Molly's uncle and that Sirius saying "cousin by marriage" is presumably the way he means...--HarryPotterRules1 (talk) 15:15, November 9, 2017 (UTC)

Do you have a link to this? I couldn't find where it specified their relationship. He could still be Molly's father (and Lucretia not her mother)... Themwhiles (talk) 11:33, September 6, 2018 (UTC)