Weird naturalization loop-hole?

[riccma02]

Hello, I am trying to figure out it I can claim dual citizenship through my father. My father was born in Italy in 1951, came over with his parents in the 1960s. He naturalized in 1970, I was born in 1990, therefore he renounced his citizenship before I was born and before the law changed in 1992. Case closed, right? But here is the catch: he naturalized at age 19, as an Italian minor. Further, he did so independently from his parents, his father did not naturalize for a few more years and his mother never did. I understand that usually, when families immigrate, minors are naturalized in with the parents, but that isn't the case here, my father would have been an adult under Italian law when his father naturalized. So my question boils down to this: is it considered a formal renunciation of citizenship if an Italian minor naturalizes to the US independent of his father? Has my father incidentally retained his Italian citizenship into adulthood despite naturalizing to the US before 1992?