Well, if that linked estate was bought 30 years after Dante's death by his son, I imagine that his son lived longer than he did.
It was customary for male Florentines of Dante's social status (that is, wealthy) not to marry at a very young age. Plus, his wedding was arranged, and tradition says it was not a happy one (it appears she didn't follow him in exile).
Anyway, let's check this trail, as long as I can.
The son in question, Pietro, was born when Pop was... drumroll... 35! Bullseye!
Pietro's male heir was another Dante, and he had it when... 49!
Dante the younger in turn was succeeded by Leonardo, this when he was... 46!
Leo proved the family champion when it came to generating a boy, fathering another Pietro at the age of 30. (Note: I'm not sure what to make of the fact that naming babies back then was as simple as recycling their grandpa's is sweet or simply the easy way out)
Pietro II did really try to improve the average. But it took five daughters to be born before the arrival of... wait for it... Dante the Third. He was 37. (another side note: as I'm following the family tree, I have to say the Alighieris appear to have had a rampant tendency to produce female heirs).
Dante III, aged 34, could not think of anything better to do than adding to the world another Pietro.
And here the curtains close: Pietro could not come up with a male heir. When he was 38 he became the father of Ginevra, who married in the Sarago family who in turn changed their name to the current form. It was 1549.
