The Kennedy story is so embroidered with legend that it’s difficult to tell the fable from historical fact. The myth-making continues with “Ethel” (8 p.m., HBO), an affectionate profile of Robert F. Kennedy’s widow and mother of his 11 children. “Ethel” is directed by Rory Kennedy, who was born in December 1968 — more than six months after her father’s assassination.

”Ethel” revisits many hardy perennials from the Kennedy image catalog — scenes of touch football games and other moments of vigorous competition; enormous gatherings of healthy, wealthy children lectured on social purpose by their politically engaged elders; and happy clips of an insular and expansive clan connected by political ambition and abiding faith.

Some interesting tidbits emerge. In addition to having 11 children (or, as her daughter puts it, spending 99 months of her life pregnant), Ethel Skakel Kennedy was passionate about animals and often had as many as 16 dogs, various horses and livestock and, for one brief shining moment, a pet seal at the family’s Hickory Hill, Va., home.

More than most Kennedy hagiographies, “Ethel” discusses Robert F. Kennedy’s work for Sen. Joseph P. McCarthy and the fact that the notorious, red-baiting senator dated two of Kennedy’s sisters.

At its most charming, “Ethel” crosses the Kennedy story with “Cheaper by the Dozen.” It’s an affectionate glance back at a huge family and two singular parents — an exercise in home-movie nostalgia laced with epic tragedy.

Tonight’s other highlights

• Liz does damage control for Jenna on “30 Rock” (7 p.m., NBC).

• The St. Louis Cardinals host the San Francisco Giants in Game 4 of the National League Championship Series (6:30 p.m., Fox).

• Marcus and Sam learn that the Navy has branded them traitors on “Last Resort” (7 p.m., ABC).

• Ava wants to feel relevant again on “Up All Night” (7:30 p.m., NBC).

• A diplomat’s daughter needs protecting on “Person of Interest” (8 p.m., CBS).

• The doctors are faced with an impossible choice on “Grey’s Anatomy” (8 p.m., ABC).

• Leslie is shocked to discover sex among the senior set on “Parks and Recreation” (8:30 p.m., NBC).

• A bureaucrat’s bombshell throws Olivia off her game on “Scandal” (9 p.m., ABC).

• Creative recycling on “It’s Always Sunny in Philadelphia” (9 p.m., FX).