Why believe that Columbus was Catalan? The original form of Columbus's surname was said to be neither Colombo nor Colón, but Colom. And Colom was a Catalan name. Apparently if it had been Colombo, it would have stayed Colombo in Castile. Colomo and Colón, the two forms the name has taken there, are simply phonetic castilianizations of Colom.
Many of his supporters and friends - Lluís de Santàngel, Joan de Coloma, Joana de la Torre, Pere Margarit, Bernat Boyl, Miquel Ballester, Antoni de Torres - were Catalans (or Valencians). His coat-of-arms, which he had before the first voyage, was Catalan.
It has been stated that an analysis of his handwriting shows that he was a native Catalan, and Columbus' mistakes in Spanish are "most likely" those of a Catalan. Without know more about the credentials of the "expert" who made this pronouncement it is difficult to comment. However, there does not appear to be a widespread acceptance of this theory. A Peruvian historian, Luis Ulloa Cisneros, was the first to publish this theory to suggest that Columbus was Catalan was in 1927.
Some linguists say that Columbus gave many of his discoveries in the New World Catalan names. One historian believes that many of the places in the Caribbean and Central America named by Columbus can be linked directly to the Balearic island of Ibiza. Some versions suggest Columbus was the illegitimate son of Prince Carlos of Viana, a mallorquin nobleman related to Ferdinand and Isabella. Columbus had a great knowledge of the work of the Mallorca cartographical school.
Names, such as Montserrat, that he gave to places in the Indies were Catalan. The admiral of the French fleet with whom he fought against the Genoese in 1476, Guillem de Casanova Colom, was Catalan, and probably a relative. His library included many Catalan books.
The historian Salvador de Madariaga believed that Columbus was from a Catalan family who fled to Genoa to escape persecution for being Jewish.
And Enrique Bayerri writes that Columbus was born in a small island in Catalunya's Ebro delta, that was called Genoa. The island later silted up, to form part of the river's flood plain.
The theory is also floated that he was the illegitimate son of a prominent Catalan sea-faring family, who had served as mercenaries in a sea battle against Castilian forces. Fighting against Ferdinand and being illegitimate were two reasons for keeping his origins obscure. But there again there could have been hundreds of just as good reasons for keeping his origins obscure.
The theory that he really was the Catalan, Cristofol Colom, who wish to disguise his past is being checked with some DNA testing. 120 Catalans have donated DNA to a team of geneticists from the Laboratory of Genetic Identification at Granada University. Similar tests on another 180 people sharing the name Colom will follow in Mallorca and Valencia. Investigators will compare the results with the DNA from Columbus' illegitimate son Hernando, whose remains lie in Seville Cathedral.
Such DNA tests are trying to see if there is a common ancestor to link the Admiral and today's Coloms. The Catalan roots has the same major weakness as the Italian roots: Columbus never wrote in Catalan and never claimed to be Catalan. The Castilian grammatical errors, as Dickson says, "are the only good card they [the Catalan theorists] have."
Christopher Columbus life before 1492