The Paleologus family, attested as living in Pesaro, Italy, from the early 16th century onwards, claimed descent from a third son of Thomas Palaiologos, called John.
As of yet, there is no independent evidence that Thomas had a son by the name John (or indeed that this John actually existed).
The most widely accepted source on the life of Thomas Palaiologos, the works of contemporary Byzantine historian George Sphrantzes, mentions all the other four children but fails to mention John.
Sprhantzes's works are not unquestionable, however.
It appears that much of it was rewritten by an editor at a later date and the timeline the works provide is somewhat questionable, having Thomas's wife Catherine give birth to one of their children at the age of 65.

The earliest source unrelated to the Paleologi of Pesaro themselves that mentions a son of Thomas by the name John is the writings of the Greek scholar Leo Allatius.
Allatius wrote in 1648, too late for his works to act as independent evidence for the descent of the Paleologus family, but he was the keeper of the Vatican Library and would have had access to its vast collection of books and records and might have deduced his findings from there.
It is possible that Allatius had access to earlier documents, now lost, which would have proven the legitimacy of the Paleologus line.
Allatius gives the sons of Thomas as "Andrea, Manuele and Ioanne".
It would be difficult to explain why Allatius, a respected and famous scholar, would simply fabricate a member of the imperial dynasty.

It is possible that John is a later corruption of the name Leone (the names are similar in their Latin form, John being rendered as Ioannes and Leone being rendered as Leonis) and there are some references to a Leone Palaiologos in Pesaro, notably a 1535 document which speaks of the “long and faithful service of Leone Palaiologos to the papal captain Giovanni della Rovere”.
Assuming that a “long and faithful” service means at least a few decades, Leone would have entered Giovanni's service in a time when Thomas's arrival to Italy would have been in recent memory and it would have been very difficult to fake kinship with him.
John could thus very well have been a real historical figure and a genuine son of Thomas Palaiologos, possibly illegitimate.
It is also possible that John was a son of either one of Thomas's historically verified sons, Andreas or Manuel (who actually had a son by that name).
If the existence of John is accepted, in some form, there is little reason to doubt the descent of the Paleologi in Pesaro.
The members of the family probably believed it themselves and by the time they arrived in England, none of their contemporaries doubted their imperial descent.
This acceptance stands in contrast to the fates of other would-be Palaiologoi in the 17th century, such as a "Theodore Palaeologus" who lived in Prague in 1603, who were convicted as forgers for their supposed claims.

The lineage of the Paleologus family remained unquestioned until modern times.
Tradition has it that during the Greek War of Independence (1821–1829), over a century after the Paleologi disappeared from history, a delegation was sent by the provisional government in Athens to find living descendants of the old imperial family.
The delegation visited places in Italy where Palaiologoi were known to have resided and even came to Cornwall, where Theodore Paleologus had lived in the 17th century.
Local tradition on Barbados has it that the delegation also sent a letter to the authorities on Barbados, inquiring if descendants of Ferdinand Paleologus still lived on the island.
The letter supposedly requested that if that was the case, the head of the family should be provided with the means of returning to Greece, with the trip paid for by the Greek government.
Ultimately, the delegation's search was in vain and they found no living embodiments of their lost empire.

In an article from 11 May 1913 in The San Francisco Call, titled Find in England, Traces of Dynasty, Once Ruled the World, identified the Paleologus family as "by des
The Paleologus family, attested as living in Pesaro, Italy, from the early 16th century onwards, claimed descent from a third son of Thomas Palaiologos, called John. As of yet, there is no independent evidence that Thomas had a son by the name John (or indeed that this John actually existed). The most widely accepted source on the life of Thomas Palaiologos, the works of contemporary Byzantine historian George Sphrantzes, mentions all the other four children but fails to mention John. Sprhantzes's works are not unquestionable, however. It appears that much of it was rewritten by an editor at a later date and the timeline the works provide is somewhat questionable, having Thomas's wife Catherine give birth to one of their children at the age of 65.
The earliest source unrelated to the Paleologi of Pesaro themselves that mentions a son of Thomas by the name John is the writings of the Greek scholar Leo Allatius. Allatius wrote in 1648, too late for his works to act as independent evidence for the descent of the Paleologus family, but he was the keeper of the Vatican Library and would have had access to its vast collection of books and records and might have deduced his findings from there. It is possible that Allatius had access to earlier documents, now lost, which would have proven the legitimacy of the Paleologus line. Allatius gives the sons of Thomas as "Andrea, Manuele and Ioanne". It would be difficult to explain why Allatius, a respected and famous scholar, would simply fabricate a member of the imperial dynasty.
It is possible that John is a later corruption of the name Leone (the names are similar in their Latin form, John being rendered as Ioannes and Leone being rendered as Leonis) and there are some references to a Leone Palaiologos in Pesaro, notably a 1535 document which speaks of the “long and faithful service of Leone Palaiologos to the papal captain Giovanni della Rovere”. Assuming that a “long and faithful” service means at least a few decades, Leone would have entered Giovanni's service in a time when Thomas's arrival to Italy would have been in recent memory and it would have been very difficult to fake kinship with him. John could thus very well have been a real historical figure and a genuine son of Thomas Palaiologos, possibly illegitimate. It is also possible that John was a son of either one of Thomas's historically verified sons, Andreas or Manuel (who actually had a son by that name). If the existence of John is accepted, in some form, there is little reason to doubt the descent of the Paleologi in Pesaro. The members of the family probably believed it themselves and by the time they arrived in England, none of their contemporaries doubted their imperial descent. This acceptance stands in contrast to the fates of other would-be Palaiologoi in the 17th century, such as a "Theodore Palaeologus" who lived in Prague in 1603, who were convicted as forgers for their supposed claims.
The lineage of the Paleologus family remained unquestioned until modern times. Tradition has it that during the Greek War of Independence (1821–1829), over a century after the Paleologi disappeared from history, a delegation was sent by the provisional government in Athens to find living descendants of the old imperial family. The delegation visited places in Italy where Palaiologoi were known to have resided and even came to Cornwall, where Theodore Paleologus had lived in the 17th century. Local tradition on Barbados has it that the delegation also sent a letter to the authorities on Barbados, inquiring if descendants of Ferdinand Paleologus still lived on the island. The letter supposedly requested that if that was the case, the head of the family should be provided with the means of returning to Greece, with the trip paid for by the Greek government. Ultimately, the delegation's search was in vain and they found no living embodiments of their lost empire.
In an article from 11 May 1913 in The San Francisco Call, titled Find in England, Traces of Dynasty, Once Ruled the World, identified the Paleologus family as "by des
Paleologus of Pesaro