Somebody, frequently an Ordinary High-School Student, discovers something: a photo, a family record, etc., that reveals some long-lost ancestor or unknown relative belonged to some particular unusual culture. This leads the person to realize they themselves are, technically, at least, a part of that culture too.
Suddenly, they become absolutely entranced by the notion of being part of this new group. The character begins researching, reading all about the culture, it's history and background, and famous people who are a part of it. They start to decorate with tribal trinkets or symbols, changes their clothing style to incorporate "traditional" parts of the garb, and may even begin to act in the manner that the group is supposedly supposed to act like. This will usually start to annoy their friends and possibly offend people of the particular culture who have known about it their whole lives, as the newcomer is behaving more like a stereotype than a real human being, and could end up getting them a Pretender Diss.
This trope will almost always end with a Snap Back, where the character realizes they are subsuming who they really are in favor of this, and either give up the new culture entirely, or, depending on the continuity of the series, may still keep some subtle hints to it as acknowledgment without obsession. It seems to be a method by creators to add a bit of flavor to a character or to explore the issues of cultural identity.
See also Foreign Culture Fetish, Going Native, One-Drop Rule, "Rediscovering Roots" Trip.
Examples:
- A large number of advertisements for DNA testing services (i.e. Ancestry) use this gimmick. Often the subject will think they were, say, of Scottish descent; upon learning they were really of German descent the whole time, they will suddenly throw out their entire kilt collection in favor of lederhosen.
- Played for laughs in Thinking In Little Green Boxes, where Arthur Wilson (aka Harry Potter), despite having been raised by a Canadian in New York, immediately starts speaking in a British accent upon discovering that his biological parents were British. This is really due to his adoptive father rubbing off on him.
- Crazy Ex-Girlfriend: Darryl discovered he had a Chippewa great-grandparent and promptly changed his surname to "Whitefeather", bought a bunch of Native American-inspired decor from a flea market, and asked his employees to call him "Chief".
- Parodied in an episode of How I Met Your Mother: Barney and his black half-brother James were raised by their mom, and they never knew who their fathers are. Then they meet James' dad, an African-American minister, for the first time. Barney, who desperately longs for a father figure, manages to convince himself the minister is his dad too, despite the fact that he has pale white skin and blond hair. Barney then starts acting like a steterotypical African-American, and it takes a while for his friends to make him see the minister couldn't possibly be his father.
- Mac in It's Always Sunny in Philadelphia changes his entire personality when he learns from his mother that he is Dutch instead of Irish, which greatly irritates his friends. It's later revealed that they paid his mother to lie about his ancestry. In reality, Mac has always been Irish, and they knew that this trope was going to be in play for him during their trip to Ireland, but he turned out to be even more obnoxious about being Dutch.
- Worf from Star Trek: The Next Generation was orphaned at a young age and raised by humans in the Federation. He should normally have the same morals and cultural bias as any other Federation citizen, but instead he acts like a transplanted foreigner because he's so into being a Klingon. His dealings with other Klingons are complicated by the fact that they generally don't live up to the idealized image he patterned himself after.
- Played for laughs on Will & Grace, when Jack gets a postcard from his mother briefly saying that his father was "a black boy". He doesn't change how he acts, but insists that everyone treat him differently. Turns out his father was one of a family of Irish-Catholic brothers whose surname was Black.
- In Kevin & Kell, Fiona Fennec, once her fennec ears grow in, begins to explore and embrace the dress and style of her fennec ancestry. She becomes disillusioned when she realizes the fennec community she has joined online is rather hateful and spiteful of outsiders, but ultimately decides to still appreciate her background and wears traditional colors rather than the full outfits.
- Kimi from All Grown Up!, despite knowing she was Japanese her entire life, really only has it click for her while working on a family tree. She begins to wear kimonos and decorates her bedroom with Japanese furniture and decorations. She changes her mind after seeing her stepbrother Chuckie is upset by her excluding him from her background.
- Ginger Foutley of As Told by Ginger finds a photograph of her paternal grandfather in an album and realizes she's one-quarter Jewish. Upon discovering this, she asks her family to celebrate Hanukkah in lieu of celebrating Christmas that year, until her friends declare she's taking the whole Jewish thing too far and Ginger hastily corrects this so she can celebrate both at the same time. Meanwhile, Carl, who already doesn't really believe in the spirit of Christmas, suggests celebrating Kwanzaa as well and comes to Ginger's holiday party wearing a dashiki and playing reggae spoof-Christmas songs.
- Peter Griffin of Family Guy has done this to varying degrees more than once, though usually to a more extreme and offensive end. He discovers a black ancestor and immediately changes from his "slave name" and wears African clothing. Less extreme were the times he discovered being technically Mexican or Irish.
- High School U.S.A.: In the episode where everyone is sweating the Rehearsal Practice SATs Cassandra comes to school wearing a full Native American outfit and facepaint, claiming that since she's part Native American (she's not) colleges have to let her in. "It's the law."
Amber: You're so lucky. Why weren't my people slaughtered?
- King of the Hill: In "Orange You Sad I Did Say Banana?", Kahn gets a pool as a way to impress Ted Wassanasong, but is alarmed after Ted criticizes him for being too Americanized and calls him a "banana" (yellow outside, white inside). Afterwards, Kahn goes to extremes in making his family reconnect to their Laotian roots, e.g. turning their new pool into a reflecting pond and only eating Laotian dishes, much to their frustration. However, when he's talked into joining a guerilla squad planning to overthrow the communist government, he remembers he left Laos because he wanted to escape people telling him how to live, so he tells Ted off and embraces his American lifestyle again.
- Spike in My Little Pony: Friendship Is Magic, in the season 2 episode Dragon Quest, decides to learn more about his dragon heritage. Not a huge personality shift, but he does realize that the dragons he's run into are basically a bunch of bullies and leaves them go back to the ponies.
- Done by Cartman of South Park in his Luke, I Might Be Your Father plot (in the episode Cartman's Mom is a Dirty Slut). He takes on Black, Native American and other stereotypes depending on who he thinks his father is at different points.
