Most Believable Siblings in Film/TV

Hayley Mills and Hayley Mills in The Parent Trap

Wow, I can’t believe you left off Laura Linney and Mark Ruffalo in “You Can Count on Me,” hands down one of the best representations of siblings on film and career defining moments for both actors.

Peter Krause/Michael C. Hall/Lauren Ambrose in Six Feet Under, plus they all look like they could have been Frances Conroy's children.

Kyra Sedgwick/Julia Roberts in Something To Talk About

James Gandolfini and Aida Turturro as Tony and Janice Soprano.

Joaquin Phoenix and Mel Gibson definitely don't look like brothers. The three actresses from "Hannah and her Sisters" don't look like siblings either.

You listed the worst ever combinations of siblings, OP - thanks for the laugh!!

Albert Brooks and Rob Morrow in Mother

Kyra and Julia should have added Sarah Jessica as the third sister.

Ted Knight and Jack Cassidy in the MTM show.

Kelsey Grammer and David Hyde Pierce on Frasier.

Valerie & Julie

Lange, Pfeiffer, and Leigh

Jake and Maggie Gyllenhaal captured that perfect tension of teasing love/hate sibilings have in Donnie Darko, which was pitch perfect.

The kids from I’ll Fly Away.

Kelsey Grammer and David Hyde Pierce, on “Frasier”

^agreed on Frasier and Niles.

The single best thing about the dire last season of Six Feet Under is Billy talking Brenda to death.

Well Luke and Leia lose since they made out lol

agree with r17.

Funny, you listed Rachel Griffiths and my first thought was the super-obvious Brothers & Sisters, with her playing sister to Calista Flockhart, Matthew Rhys, Dave Annable and Balthasar Getty. I think the relationships among the siblings and their parents were very true to life.

Idk if they count, but Jack & Meg White. Even though they were actually a married couple for years, their chemistry is so weird and their looks so strange in the same type of way that they could plausibly pass as siblings.

Michael and Connie Corleone

R3 Except for the fact that Frances Conroy is way too young to be the Mother of Peter Krause (only 12 years older) I'd agree.

There are twelve years olds who get pregnant.

R25 She'd have needed to be pregnant at 11 and given birth at 12.

When I watched the first episode of Frasier I was absolutely certain Kelsey Grammer and David Hyde Pierce were related.

Julia Louis-Dreyfus and Hamish Linklater had great chemistry as siblings on the New Adventures of Old Christine. Jennifer Jason Leigh isn't quite Laura Linney but she's good at playing an aggrieved sister: to Mare Winningham in Georgia, Mary-Louise Parker on Weeds, Nicole Kidman in Margo at the Wedding.

Joaquin and River Phoenix didn’t look like brothers either R6, it’s not a deal breaker.

R29 Joaquin seems more like Casey Affleck’s brother.

Jessica Lange, Michelle Pfeiffer, and Jennifer Jason-Leigh in A Thousand Acres.

R31, Yes.

Nick, Heath, Jarrod, Audra, the barn's on fire!

Billy and Brenda

Barbra and Mimi Rogers in The Mirror Has Two Faces. I felt their sisterhood so hard.

[quote] Joaquin and River Phoenix didn’t look like brothers either [R6], it’s not a deal breaker.

Wasn’t it speculated that River has a different daddy than the rest of the siblings? Lots of free cock on the commune for Ma Phoenix to choose from, I’m sure!

[quote] Except for the fact that Frances Conroy is way too young to be the Mother of Peter Krause (only 12 years older)

It worked because Frances was able to convincingly pass as a woman ten years older than her actual age.

Sam and Lindsay Weir on Freaks & Geeks

Bryce Johnson & Cole Williams in HARRY + MAX.

Geena Davis and Lori Petty in A League of Their Own

Robert DeNiro and Christopher Lloyd in Marvin's Room. They really do have a lot of common mannerisms. I never noticed before, but ever since seeing the movie, I think of one whenever I see the other.

Not Christopher Lloyd. Dan Hedaya.

Martin Landau & Jerry Orbach in [italic]Crimes and Misdemeanors[/italic]

And I agree with previous mentions of Pierce/Grammer and Roberts/Sedgwick.

Meg Ryan & Jennifer Jason Leigh in In the Cut.

Sarah Paulson and Poppy Montgomery in The Other Sister.

Definitely NOT Eve Plumb and Maureen McCormick and Susan Olsen!

The most believable and accurate presentation of adult siblings was Monica and Ross on Friends. They were competitive, annoying to each other, harbored childhood resentments but overwhelming all of that was how much they clearly loved each other. Some of the specifics of their relationship (like the running gag that Monica was always treated as a second class kid to their parents favorite, Ross) were so spot on that they made me laugh out loud.