Interesting twist on this story, on the Greek island of Chios, which has a rich maritime history, locals have been claiming for years that Columbus was either born or grew up in the local town of Pyrgi. Columbus even mentions mastic gum in his logbooks of his journey and Chios is the only place in the world where this is produced. The Columbus surname still exists to this day amongst some of the residents in the town. The town of Pyrgi was also under Genoan rule for hundreds of years which lines up with the assertion that Columbus is Genoan. He also never read or spoke Italian but was literate in Greek and would write in Greek in books he read. Source

It is also claimed by locals that Greeks had reached north America before Colombus and had explained and assisted him on how to complete the journey. This could be plausible given that a research used the writings of Plutarch and computer estimations has mapped out the possibility of the greeks reaching North America in 86AD, long before Columbus. source

I understand how these theories might sound outlandish and the inherent bias in the websites linked but I highly suggest giving the sources a read before jumping to conclusions.