[verbify]

Surnames are heritable through the male line only. Genes are heritable through both parents. Wealth is some societies is heritable mostly through the male line, and in other societies through both lines.

Assuming that in the ~584 odd years from the study to the present day that 20 generations passed (average of 30 years per generation), the specific great-great-grandparent who passed on that name has roughly a 0.5^30 on that person (which is an infinitesimally small number).

However, rich people usually marry rich people. It's likely these results aren't just direct inheritance, or direct genetics, but it shows stratification within Italian society.