Prof Vecce, from the University of Naples L’Orientale, believes she was kidnapped from Circassia, possibly by Tartars, and then shipped across the Black Sea to Constantinople and from there to Venice.
She was then acquired by a family in Florence for whom she worked as a wet nurse.
It was there that she was made pregnant by Leonardo’s father, Ser Piero da Vinci, in the summer of 1451.
Once the baby was born Caterina was swiftly married off, with a generous dowry, to a local smallholder with whom she went on to have five children.
Slaves from there in medieval Italy? Sure.
Worrying about the marital status of a wet nurse? Don’t think so. By definition she had – to be a wet nurse – to be a mother of at least one already.
The general story is entirely possible. That one detail not so much.