The mice the two independent labs used were several generations distant from the original strain or grown from preserved embryos, and in that interval, any number of changes could have happened in gene sequences or to affect how the animal uses the gene.
The Benedettis begin as peasants and become wealthy landowners, but their prosperity and power derive from an original sin, committed in the seventeen-nineties, for which future generations have never received full absolution.
It's really quite profound when you think about it: a founding father granting future generations permission to make changes to a document with the ink barely dry on the original.