Columbus was from a Jewish Background?

I think very unlikely. The genetic evidence seems poor. For a long time it wasn’t clear if the body they thought was Columbus was even him, and the quality of the ‘match; with the body known to be his son Hernando was by no means air-tight. Any anyway, there is a lot of genetic overlap in Mediterranean populations, for example, my own Y chromosome and (necessarily maternal) mitochondrial haplogroups are shared by both Steven Pinker and Corsican Napoleon, who I doubt are related except to Great-Grandpa Natufian who invented the Neolithic in that cave they found his 10,000 year-old bones in, just east of what is now Ben Gurion airport, and who apparently had a lot of far-future descendants.

There are good records of Columbus being born in Genoa, and there were also very, very few Jews living in Italy prior to the wave of immigration of those fleeing the Spanish Inquisition. However, by the 1480, many Jews started arriving, including some of the original co-financiers of the voyages who were active at the historically famous Bank of St George. This influx includes my maternal line, which landed in Florence around the time of Michelangelo and Machiavelli. Genoa got a lot too, and their rivals in Venice saw the Jewish population “explode” to several thousand over 25 years, the disruption of which provoked the edict to create Europe’s first ghetto of segregated residential zoning. Must have been just like the more recent experiences MS-13 and Tren de Aragua (joking, for Northern Italy it was on-net more like a windfall, like getting the refugees which worked on the Manhattan Project).

Columbus’ signature was pretty Christian, “S / S.A.S. / X.M.Y / Xpo Ferens” is the abbreviation of “Servus / Suplex Altissimi Salvatoris / Christus Maria Yosef” = “The humble servant of Christ, the Supreme Savior, Mary and Joseph, Christ-Bearer” (That’s what “Christopher” means).

Now, some years ago, another scholar tried to make a similar claims based on something mysterious Columbus did with his letters to his son Diego, which you can see scans of in “The Authentic Letters of Columbus”. In those letters he wrote some kind of two-letter abbreviation in the upper left corner, which is hard to make out but looks kind of like a capital B in cursive and written from right-to-left with some kind of loop-de-loop flourish to the left. Now, it is true that many Jewish letters from that time have two Hebrew letters in that corner, but to my eye I don’t see them in whatever Columbus put there in those letters to Diego.

If he does turn out to be Jewish the phrase “a man among the gentiles” may turn out to have some meaning beyond awkward phrasing.