The 68-year-old actress made headlines with a recent Vanity Fair story in which she claimed that Ronan might have been conceived with her ex-husband, "Ol' Blue Eyes."
Ronan, whom everyone assumed was Woody Allen's son, appeared to the the news in stride.
"Listen, we're all *possibly* Frank Sinatra's son," the 25-year-old quipped Wednesday.
The younger Farrow isn't on good terms with the man he assumed was his biological father. Allen famously left Mia for her adopted daughter, Soon-Yi, in 1992. Their relationship supposedly began in 1991, when Soon-Yi was 21 and Allen was 56.
"Happy father's day -- or as they call it in my family, happy brother-in-law's day," Ronan wrote on Father's Day in 2012.