Blue Bloods' Len Cariou Isn't Really That Much Older Than His TV Son Tom Selleck
From the first episode on, "Blue Bloods" has always followed the lives of a family with a deep-rooted history in the New York City Police Department, with the unquestionable patriarch of this law-abiding family being the now-retired New York City Police Commissioner Henry Reagan (Len Cariou). That said, the central figure in the show is his son, Frank Reagan (played by Tom Selleck), who has since taken over the position of commissioner, while his children hold various positions in the NYPD and the district attorney's office.
In the show, Cariou's character is assumed to be a couple of decades older than Selleck's. However, even though the show sells this relationship so well that you believe the age difference, the truth is that it might have been more appropriate to have Henry and Frank be brothers, rather than father and son.
It's amazing what a little hair dye can do for your looks
Despite being portrayed as Selleck's father on "Blue Bloods", Cariou is barely his senior — Selleck was born in 1945 (per Walk of Fame), and Cariou was born in 1939 (via TCM), meaning the actual age difference between them is only about five years.
Cariou's white hair and Selleck's darker brown help give the illusion that one is much older than the other, of course. Frank's children, on the other hand, are played by actors that have much more realistic ages when compared to Selleck. Donnie Wahlberg, Bridget Moynahan, and Will Estes all play Frank's children on the show and are all between about 25 and 35 years of age younger than Selleck — a much more believable age gap between a father and his children.
Both Selleck and Cariou got their acting start in the 1960s, but Selleck would become a household name when he was cast as Thomas Magnum in the CBS hit "Magnum P.I." Cariou, meanwhile, has earned over 80 onscreen credits throughout his career.