I’m choosing to do this as a chronicling of backstory retcons (plus a couple of important firsts) because it would be too much to do the whole thing, and I’m going to include the various changes to Magneto’s backstory because they’re kind of necessary. The dates listed are release date, not cover date.
March 1964 (X-Men vol. 1 #4) -- It’s Wanda, no last name. She’s a mutant, part of the Brotherhood of Evil Mutants. She’s from Central Europe. She has an older brother named Pietro, and he promised their parents that he would take care of her.
March 1965 (Avengers vol. 1 #16) -- Wanda’s an Avenger now.
November 1966 (Thor vol. 1 #134) -- We learn that Wanda and Pietro, who are now twins, are connected to Wundagore Mountain and that there was a massive “blinding light” on the night they were born. This was maybe an aborted attempt to retcon them into not being mutants (their powers are referred to as “mutant-type” for some reason), but it goes nowhere.
May 1974 (Giant Size Avengers #1) -- Wanda and Pietro finally have a backstory. They are the children of US-American superheroes Madeline and Robert Frank (aka Miss America and The Whizzer). They were born on Wundagore Mountain, but their mother died and their father abandoned them. They were subsequently raised in the High Evolutionary’s citadel, but they ran away because it was weird being around all those talking animals.
June 1974 - February 1975 (Avengers vol. 1 #127-134; Giant Size Avengers #2 & 4) -- Agatha’s here, and she’s teaching Wanda magic. Wanda is now a mutant AND a witch.
December 1977 - September 1979 (Avengers vol. 1 #166 & 181-187; X-Men vol. 1 #125) -- Origin Story: The Good One. Wanda and Pietro are not the Franks’ kids and were not raised in the High Evolutionary’s citadel. They were raised by Django and Marya Maximoff, a Roma couple from Bulgaria (Transia, the town they’re from, will later become a country of its own), and it is implied that they don’t remember this because they suppressed their own memories. However, Django and Marya are not their birth parents. Their birth mother came to Wundagore Mountain, heavily pregnant, fleeing their father. She gave birth in the citadel, then left because she did not want to be alive anymore.
Meanwhile, Chris Claremont comes up with the idea for Magda, Magneto’s mysterious dead wife, but before the issue introducing her can even come out, John Byrne and some other guys go behind Claremont’s back and make Magda Wanda and Pietro’s mother. Which makes Magneto the husband their mother was running from and thus... None of the living characters know they are related, and it is editorial’s intention that they will never find out, though the connection is acknowledged openly in the letters column.
August 1981 (Uncanny X-Men vol. 1 #150) -- Claremont begins the long process of turning Magneto into a hero, and with that, we learn Magneto’s backstory as a Holocaust survivor. Claremont continues to add to this for the rest of his initial X-Men tenure (through 1991), but crucially, he never has him say that he’s Jewish. You’re supposed to understand that he is, and most of the audience does understand. It is very, very obvious (we even get a trip to Israel), BUT he does not say the exact words, “I am Jewish.”
November 1982 (Vision & the Scarlet Witch vol. 1 #4) -- The characters aren’t supposed to find out they’re related? Forget that. They all know now. I would argue that this issue also makes it obvious that Magneto is Jewish, but whatever, he doesn’t say, “I am Jewish.”
October 1985 (Vision & the Scarlet Witch vol. 2 #5) -- This is the earliest reference I can find to Magda being Romani. It feels like that can’t be the first time that was confirmed, but this post needs to get done some time.
October 1987 (New Mutants vol. 1 #61) -- Another “earliest reference I can find” scenario. I think this is the first time Magneto mentions being from Poland. At any rate, it is a time he mentions being from Poland, and it gets retconned anyway.
July 1993 (X-Men Unlimited vol. 1 #2) -- Due to editorial meddling, Magneto became a villain again in 1991, and according to comic book legend, editor-in-chief Bob Harras thought that Magneto being Jewish and a supervillain was proooooooblemaaaaaaatic. And if he can’t be both at the same time, one’s gotta go. Enter Gabrielle Haller, who is here to give a Ted Talk explaining Magneto’s new backstory. He’s Sinti Romani. That’s the change.
December 1997 (X-Men vol. 2 #72) -- It is revealed that the Erik Lensherr identity was an alias created by document forger Georg Odekirk in order to help Magneto hide from the authorities and find Magda... by pretending to be Sinti. Which, to me, implies that Magda herself was Sinti specifically, not Roma. Either way, Magneto says he’s not Romani, but once again does not say he’s Jewish.
September 2008 - January 2009 (X-Men: Magneto Testament #1-5) -- Magneto is officially, definitely Jewish. For real this time. No more ambiguity. He’s also German now, instead of Polish, and his name is Max Eisenhardt.
December 2014 (Avengers & X-Men: AXIS #7) -- Rick Remender, who is clearly invested in Wanda and Magneto’s relationship, is forced, possibly at gunpoint, to make them not related. This is revealed via a spell going wrong and not affecting Magneto when it’s supposed to affect Wanda’s family, which is the dictionary definition of “plausible deniability.”
January 2015 - June 2015 (Uncanny Avengers vol. 2 #1-5) -- Wanda and Pietro go to the High Evolutionary to figure out what their brand new backstory is. Turns out that, according to the High Evolutionary, they are not mutants and got their powers from being experimented on by him as babies. Their birth parents were their adoptive parents Django and Marya all along, which would make them Roma (not Sinti)... but something is weird about this reveal because Vision finds out there is more to the story and refuses to tell Wanda what it is or that he discovered any information at all.
March 2016 - January 2017 (Scarlet Witch vol. 2 #4-14) -- Nevermind, Django and Marya weren’t Wanda’s biological parents. Django is her uncle. His sister Natalya is her birth mother and a witch, and “the Scarlet Witch” is now a legacy title. Wanda was born in Serbia, but how that intersects with the Chthon thing is not explained. And Wanda’s dad is... the guy who murdered her mother. Who? Doesn’t say.
December 2017 - July 2019 -- A bonus! Marvel gives up on pretending Wanda and Magneto are not related... but mostly outside of comics. The official Marvel website runs articles just... saying they’re related. Official merchandise says they’re related. The mainline comics don’t touch it, but things are very suspicious.
