New findings based on research that spanned over 20 years suggest that Christopher Columbus was likely of Spanish and Sephardic Jewish descent, according to a new genetic study conducted by Spanish scientists, aiming to solve a five-century-old mystery.

The scientists believe that the explorer who changed the course of human history by discovering the Americas was probably born in Valencia, Spain. They also believe he may have concealed his Jewish identity or converted to Catholicism to avoid religious persecution.

At that time, around 300,000 Jews lived in Spain before being ordered, along with Muslims, to convert to Catholicism or leave the country in 1492 — the same year Columbus landed in the Americas. Some Jews fled to Thessaloniki, which was then part of the Ottoman Empire.

Until now, the traditional theory — though questioned by many historians — held that Columbus was Italian, originating from Genoa. However, as the BBC notes, there have been many contradictory theories about the explorer’s origin, ranging from Poland to Great Britain, and from Portugal and Hungary to even Greece.

The new findings are the result of over two decades of research.

The study began in 2003 when José Antonio Lorente, a forensic professor at the University of Granada, and historian Marcial Castro, examined Columbus’s remains in the Cathedral of Seville.

Columbus died in Valladolid, Spain, in 1506 but wished to be buried on the island of Hispaniola in the Caribbean. His remains were moved there in 1542, though centuries later, they were transferred to Cuba before finally resting in Seville.

Researchers also took DNA samples from Columbus’s tomb, as well as from the bones of his son, Hernando, and his brother, Diego. They then compared the genetic data with that of historical figures and relatives of the explorer.

“We have a very partial but sufficient DNA sample from Christopher Columbus,” Lorente explained in a television program where the findings were presented.

He added that while we don’t know exactly where Columbus was born, it was likely in the western Mediterranean, specifically in the region of Spain. During that period, the Jewish presence on the Italian peninsula was relatively limited, making Italian ancestry less likely.

However, even this research has not been universally accepted, as noted by the Guardian. Other scientists are calling for the Spanish researchers to publish their findings in a peer-reviewed journal so that the scientific community can assess them.