Christopher Guest's new TV series Family Tree, which premiered last night on HBO, is similar to but less pointed than his best known works. Starting with 1996's Waiting for Guffman, the director-actor has orchestrated a string of improvised farces in a mostly pseudo-documentary format that roast specific, unexamined cultures: Midwestern community theater geeks (Guffman), dog-show people (Best in Show), folk singers and their groupies (A Mighty Wind) and indie actors with Oscar buzz (For Your Consideration). Repeatedly, you get the feeling that Guest thinks he is smarter than the people that he and his repertory hypothesize, but these characters feel so lived-in that they are endearing regardless. Their doofiness is an asset for everyone involved, at least until they're punished for it in Guest's characteristically dark codas of dashed dreams and ruined lives.

Family Tree, on the other hand, focuses on no such subset. Its protagonist, Tom Chadwick (Chris O'Dowd), is a 30-year-old Brit (with an Irish accent, thanks to his parents divorce) who finds direction in life when an inheritance spurs him on a quest for a full picture of his genealogy. This brings him not just in frequent contact with his father (Michael McKean), stepmother (Lisa Palfrey) and sister Bea (Nina Conti), but also a host of eccentrics who knew now deceased members of his extended family. A lot of these eccentrics are elderly, and if Family Tree expands our understanding of Christopher Guest's worldview at all, it's to say that he thinks old people are inherently funny and mock-worthy, too.

Along the way, we see flashes of Guest signatures like weird inventions (his father shows the camera a cooling shoe tree with a fan attached, while Jim Piddock's antiques expert character Mr. Pfister has a hobby of crafting landmarks in bottles), fictional sendups of existing pop culture and theater jokes. The series is delicately funny — maybe too delicate. Conti, whose character says wildly inappropriate things via a therapy puppet monkey called Monk, and Palfrey, who plays an off-the-wall ESL foreigner with the indelibility of Jennifer Coolidge, are fascinating nutjobs, but O'Dowd feels miscast. He is a likeable actor, but not quite weird enough or naturally hilarious to carry this series. He's so often a straight man to whatever weirdo is sitting across from him. He inhabits this dry character well (“Good. You know, crying myself to sleep, but fine," is his response when asked how he's doing), but both he and his genealogical quest are unremarkable and lacking the inherent tension that Guest's movies ramp up to.

That said, I've watched four episodes of this show and have laughed Guffman-hard at least once during each. One time, however, during the fourth (and as yet best) episode, it was at a fart joke. What I liked most about the first episode is the scene above, in which Tom is on a date with a woman named Ellie, ingeniously played by Natalie Walter. Her balance between idiocy and awareness is athletic.

In my experience, each improvised Guest project since Guffman has been less rewarding (I may like For Your Consideration more than A Mighty Wind, but just barely). Family Tree continues the trend. Granted, I haven't seen its last four episodes, which move the setting from London to America and prominently feature Guest regulars like Bob Balaban, Ed Begley, Jr., Fred Willard and Guest himself (out of all of them, only Begley appears in the first half of the series, and it's a cameo).

Also, part of the joy of Christopher Guest movies comes in repeat viewings, which TV cultivates less of than film, for whatever reason. And with more pop cultural stuff than ever to wrap our brains around, it's never been harder to revisit and meditate. Gone are my college days when I could watch Guffman, rewind the VHS and immediately watch it again. The intricacies that reveal themselves through repetition go undetected. It's a different world, but Guest is just as amused and revolted by it.