Wälsungenblut (a medium length novella about incestuous fraternal Jewish twins, whose title in English would be roughly Blood of the Wälsungs) is probably one of Thomas Mann's most controversial and problematic works of shorter fiction, having had both accusations of overt anti-Semitism and that the novella is basically a rather nasty and innuendo-heavy roman à clef levelled at it, with Mann's in-laws, with the Pringsheims, playing the main character parts (seeing that the Pringsheims were, in fact, secular Jews, and that Thomas Mann's wife Katia did have a very close and intimate personal relationship with her twin brother Klaus, rather similar in some ways to the two main protagonists in Wälsungenblut, to Sigmund and Sieglinde Aarenhold, although it must and really should be mentioned that there NEVER were any even remote accusations of actual incest between Klaus and Katja Pringsheim or even considerations of and for this, and that the vast majority of the issues and accusations surrounding the novella itself were therefore most likely due to some nastily putrid, judgmental and societal busybody Munich gossips).
However and the above having been said, and yes, in my own humble opinion, it is indeed and still somewhat problematic and potentially worrisome that Wälsungenblut originally did have an ending that might well be considered at least potentially anti-Semitic. For after their incestuous sexual rendez-vous (upon having attended a performance of Richard Wagner's opera Die Walküre and which also features two incestuous twins named Sigmund and Sieglinde), Sieglinde, asking Sigmund about the consequences of this for her (I am assuming) Christian fiancé von Beckerath, is answered simply and bluntly in Yiddish that they have tricked him, that they have "robbed" him of taking Sieglinde's virginity (with Sigmund also calling him a goy which can often have negative connotations and is seen by many as a derogative term for someone who is not Jewish). But indeed, in the more readily available later version of Wälsungenblut (and the one contained in most published anthologies) that same ending has been made considerably less pointed (although Thomas Mann seemingly only grudgingly had agreed to this), with Sigmund instead claiming that what happened (that the twins' incest) should be seen as a positive, that it would actually render von Beckerath's trivial and hence worthless life into a somewhat less trivial, more positive and praiseworthy existence.
And I have, in fact, read both versions of Mann's Wälsungenblut (the original as a photocopy for a graduate level course on Thomas Mann's short fiction), and quite frankly (and personally), although I do see the potential issues with the original ending (and its inherent dangers, its cynical nastiness of von Beckerath not only having been sexually tricked by Sigmund and Sieglinde but also having perhaps even deserved this simply due to who he is and what his culture and his background are), and while the altered and changed second ending is perhaps more so-called politically correct, it has to me, in fact, always tended to actually feel a bit potentially nastier and vicious than the first, than the original ending (as the second, the altered ending is really to and for me much more obviously and clearly degrading and denigrating of von Beckerath as a person, with Sigmund basically labeling his life, his very existence as trivial, as worthless, and as only having been made somewhat and remotely less so by the twins' incest, by Sieglinde's sexual tryst with he twin brother Sigmund).
So does the narrative of Wälsungenblut and especially that original ending expose Thomas Mann as an anti-Semitic bigot? Are some of Wälsungenblut's thematics autobiographical and thus specifically about Katia Pringsheim's close relationship to her twin brother? Is Thomas Mann therefore suggesting by means of this novella that his wife's relationship with Klaus Pringsheim was perhaps unsavoury, and is he thus perhaps also using literature as a kind of revenge for having married Katia Pringsheim more for societal and status reasons, as a marriage of bourgeois convenience? Or is the entire premise of Wälsungenblut perhaps an almost too sly and too clever ironic attempt to ridicule the notoriously anti-Semitic Richard Wagner by suggesting that there really is no difference between Wotan's mystical incestuous twins Sigmund and Sieglinde and a pair of incestuous and decadent bourgeois Jewish twins (who even have the same names)?
Frankly, I for one consider Wälsungenblut as much too multilayered and intricate a story, a plot, to have but one possible and even probable interpretation, and in my opinion (the open-ended questions posed above notwithstanding), it is primarily a novella that critically presents and condemns decadence and self absorption, and all of the other issues and themes presented and featured (even when one considers the implications of anti-Semitism, of racism and links to the operas of Richard Wagner) are basically subservient to this one main subject matter. For Sigmund, especially, is portrayed and depicted, described as decadence personified, as an individual who has decided to live (with his twin sister Sieglinde) an existence against both societal and genetical norms. Thus by living basically and specifically, willfully against bourgeois normality, Sigmund is in many ways rather akin to Thomas Mann's other and more well known decadent artist figures (although Sigmund's arrogance and unsavoury disposition, his lifestyle choices make him more akin to Cipolla, Tristan or Gustav von Aschenbach than for example Hanno Buddenbrook and Tonio Kröger). And because Sigmund is first and foremost self involved and in love with himself (extreme narcissism), is actually described as being rather androgynous, he also and primarily sees his twin sister Sieglinde as a mirror image of himself (and thus while the twins' relationship is perhaps incestuous, the fact that they appear as mirrors of one another, also makes their love for each other more akin to extreme and unhealthy self love); Sigmund does not really love Sieglinde as a person, he simply sees her as an extension of himself and vice versa. Highly recommended, but with the caveat that while interesting and thought-provoking, Wälsungenblut is also disturbing and potentially distasteful, even nauseating (and Sigmund especially has the tendency to make the reader squirm and cringe).
And if you are, indeed, interested in reading this novella, it is generally contained in most decent collections of Thomas Mann's short fiction (however and unfortunately, usually only with the second, the altered and considered less politically incorrect ending). And as I have never read Thomas Mann in English, I am unable and also quite unwilling to make comments regarding the quality of potential translations of this or other Mann short fiction offerings (so while I do strongly recommend Wälsungenblut with the above mentioned caveats, with any English language translations, it is definitely at least somewhat also a major case of "reader beware").