Hollywood usually ignores the rules of genetics when it comes to casting family members in movies. Even some of our favorite films of all time, from "The Godfather" to "The Royal Tenenbaums" feature relatives that no combination of chromosomes could have realistically created. But every once in a while, the showbiz powers that be strike casting gold with actors who resemble each other enough to believably share a last name.

Here are 12 pairs of co-stars who you'd swear could be related.

Philip Seymour Hoffman & Jesse Plemons in 'The Master'

Who They Play: Author, philosopher, physicist and religious leader Lancaster Dodd and his skeptical son Val.

Why It Works: You don't have to be an experienced casting agent to see the striking resemblance. The round cheeks, the prominent chin, the fair skin, the blond, perfectly combed hair. But it goes beyond the obvious like hair color and skin tone — Plemons can summon Hoffman's intensity to complete the likeness.

Dustin Hoffman, Barbra Streisand & Ben Stiller in 'Meet the Fockers'

Who They Play: The eccentric Focker clan: Capoeira-loving Bernie, sex therapist Roz, and their son, male nurse Greg.

Why It Works: With all due respect to Stiller's actual parents Jerry Stiller and Anne Meara, the combination of Babs and Hoffman really does equal the compact, sarcastic, Semitic sexiness that is Ben Stiller. Watching the three of them interact is what made that comedy sequel watchable.

Anne Hathaway & Rosemarie DeWitt in 'Rachel Getting Married'

Who They Play: Not-quite-recovering addict Kym and her completely put-together sister Rachel.

Why It Works: As on-screen siblings go, Hathaway and DeWitt had enough of the same look (willowy brunettes with dark eyes and bright smiles) to pass as sisters, or maybe it's because DeWitt is such a lovely girl-next-door chameleon that she can blend in with any of her fictional kin (see her opposite Jennifer Garner in "The Odd Life of Timothy Green", Emily Blunt in "Your Sister's Sister" or even Toni Collette in "United States of Tara").

Michael Fassbender & Carey Mulligan in 'Shame'

Who They Play: Sex addict New Yorker Brandon and his equally as-troubled younger sister Sissy.

Why It Works: If you can get past the incestuous undercurrent of their obviously dysfunctional relationship, you'll see that there's something about Fassbender and Mulligan's melancholy eyes that ties them together. Yes, he's all sharp angles and she's soft and apple-cheeked, but those sad, sad eyes make it clear that they belong to each other.

Jodie Foster & Kristen Stewart in 'Panic Room'

Who They Play: Divorced New York City mom Meg Altman and her asthma-suffering tween Sarah.

Why It Works: Foster and Stewart not only match physically — beautiful and tomboyish with striking eyes — but they even sound alike. It's like Stewart was Foster's Mini-Me. These two are so similar they're like the female versions of Philip Seymour Hoffman and his "The Master" son Jesse Plemons. In fact, we propose a movie where Foster and Hoffman are the parents and Stewart and Plemons the grown-up kids. How 'bout it, David Fincher?

Johnny Depp & Keith Richards in 'Pirates of the Caribbean: At World's End' and 'On Stranger Tides'

Who They Play: Captain Jack Sparrow and his pirate papa, Captain Teague.

Why It Works: In a delicious bit of meta-casting, Gore Verbinski scored the casting coup of the '00s by convincing the legendary Rolling Stones guitarist to play Johnny Depp's on-screen dad. After all, audiences and critics had been raving for years about how much Depp played Sparrow like a pirate version of Richards. Depp and Richards in their guyliner, dreads and beloved pirate hats is one of the best parts of the swashbuckling franchise.

Robert Pattinson, Kristen Stewart & Mackenzie Foy in 'The Twilight Saga: Breaking Dawn - Part 2'

Who They Play: Newlyweds Edward and Bella Cullen and their human-vampire daughter Renesmee.

Why It Works: Forget the ridiculous name (it's a mash-up of her grandmothers' names) and take a look at young Mackenzie. Now that it seems like Pattinson and Stewart may never get their happily ever after off-camera, Foy is as good as it gets in terms of a hypothetical Robsten offspring. The beautiful 11-year-old definitely won the genetic lottery, as she is the perfect combination of Rob and Kristen's gorgeous features.

Alfre Woodard & Sanaa Lathan in 'Something New,' 'The Family That Preys,' 'Love & Basketball'

Who They Play: Mother and daughter three times over: in the underrated interracial romcom "Something New", the Tyler Perry interracial dramedy "The Family That Preys" and the fabulous indie romance "Love & Basketball."

Why It Works: After a trifecta of films that show off their considerable skills at playing mother and child, we started to wonder if maybe Lathan really is Woodard's daughter. She isn't, but they sure could've fooled us with their twin almond-shaped eyes, perfect full lips and flawless skin.

Paula Malcomson & Willow Shields in 'The Hunger Games'

Who They Play: Melancholy District 12 widow Mrs. Everdeen and her youngest daughter, Primrose.

Why It Works: In the books, dark-haired Katniss takes after their (deceased) father while little sister Prim is the spitting image of her fair-skinned, light-haired mom. And while the trilogy's devoted followers had very strong opinions about whether the main actors fit their image of the book characters, most fans agreed that Malcomson and Shields captured Suzanne Collins' description of Katniss' mother and sister.

Tony Shalhoub & Stanley Tucci in 'Big Night'

Who They Play: Immigrant brothers appropriately named Primo (Shalhoub) and Secondo (Tucci).

Why It Works: Shalhoub is Lebanese and Tucci Italian, but they were an excellent match as brothers desperate to save their family-run restaurant in this foodie-approved period drama. Maybe we were distracted by the sheer amount of delectable Italian food on display, but a thickly mustachioed Tony and a thickly eyebrowed Stanley (with slicked-back hair!) could definitely pass for fratelli.

Rupert Grint & Bonnie Wright in 'Harry Potter'

Who They Play: The youngest of the seven magical Weasley kids: Ron and his little sister Ginny.

Why It Works: We know it seems there's only one prerequisite to being a member of the Wizarding World's Weasley clan — having red hair. But while most of the movie Weasleys had to get a dye job, natural gingers Grint and Wright stood out thanks to their matching locks, alabaster skin and sea-colored eyes. Plus, after ten years and eight movies, the two seemed as familiar as on-screen siblings can be — with or without magic.

Jake & Maggie Gyllenhaal in 'Donnie Darko'

Who They Play: Post-traumatic high schooler Donnie Darko and his Harvard-bound older sister Elizabeth.

Why It Works: We know it's cheating, since these two actually share the same DNA, but there were certainly people who saw the 2001 cult indie and thought, wow, that brother and sister really look alike. And they do. Plus, of all the brother-sister pairs working in Hollywood, we think the Gyllenhaals have what it takes to go the distance like Warren Beatty and Shirley MacLaine. Eleven years later and we're still keeping fingers crossed that they work together again.