The speculation contained in J.K. Rowling's biography of Harry Potter is actually a fairly decent gloss en miniature on the subject. Unfortunately, this is a roundabout means of saying that we don't really know for sure.
On the subject of why people avoid ... er, the subject: Interestingly, the solid information that we do have largely comes to us via Albus Dumbledore and (appallingly enough) Gellert Grindelwald. This has been an issue of tremendous controversy in the Wizarding community, and I suspect that many have avoided this branch of our history simply out of revulsion for one of its few principal scholars. However, we're sufficiently removed from Grindelwald's attempted rise to power that the stigma of studying his work has faded among the younger generations, and the events of the Second Wizarding War stimulated additional interest in the Hallows. I am hoping for more and better scholarship on the subject soon.
What we do know is as follows: As Rowling relates, the three Hallows -- the Elder Wand, the Resurrection Stone, and the Cloak of Invisibility -- are thought to have been the creation of the three Peverell brothers. This is sufficient to give us a starting point, as the Peverell family was connected with the Wizarding hamlet of Godric's Hollow for the better part of two centuries as traders and craftsmen, and one of them (Ignotus) is buried at St. Clementine's there.
The Peverell brothers were as follows:
Please note that the death date I have given here is even more a matter of conjecture than his birth date. If Antioch is indeed the shadowy figure in The Tale of the Three Brothers who met his end at knifepoint, then we can assume he probably did so as an adult after creating the Elder Wand. And yes, I think he was actually the second of the three brothers to die, and not the first as is implied in the tale. Again, we'll come back to this in a little bit.
If Beedle's account is accurate (and that is a VERY big if), is Beatrice the fiancée of the tale, in reality a wife? Is the fiancée actually another woman whom Cadmus hoped to marry after losing his first wife, or was it only ever just Beatrice? Or -- worse yet -- did he actually lose a wife and a fiancée in quick succession? We don't know, but either way, we have the portrait of a young man wracked by guilt and consumed with the idea of recovering what had been lost.
Cadmus' daughter is probably the descendant who inherited the Resurrection Stone, starting a chain that eventually ended with a Gaunt descendant (He-Who-Must-Not-Be-Named) and subsequently Albus Dumbledore and Harry Potter in the 20th century. If Cadmus did commit suicide, that may explain why there is no subsequent mention of him in St. Clementine's records: The stigma against suicide in the Wizarding community was much stronger in this era than it is at present, and Cadmus would have been buried quietly in an unmarked grave in unconsecrated ground. Whether this was in Godric's Hollow is anyone's guess, and of course, it's always possible that he died elsewhere under vastly different circumstances.
There is no mention of the Hallows prior to the 13th century, which further strengthens our belief that the Peverells are in fact responsible for their creation. A variety of very powerful magical artifacts in lore certainly existed both before and after under different names, but the Hallows seem to be a very singular construction.
Continued below with a discussion of the Resurrection Stone.
As written in Hogwarts : a History :
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