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Lisa is quite eclectic in her knowledge and is notably more concerned with world affairs and problems than her cohorts. Lisa shares her intellect and overachieving personality traits with other female members of the Simpson family (revealed that Simpson males inherit a gene on the Y chromosome that prevents them from channeling their intellect), such traits are not seen within the Bouvier family. Lisa also deeply values her integrity, as demonstrated when she cheats on a test in The Wind in the Willows to attain her highest grade of A+++, but later admits her dishonesty to an unreceptive Principal Skinner. (She later re-grades the test as an F.) Despite her intellect, Lisa has received detention, like her brother Bart, quite a number of times, often because of her rebellious and sometimes bitter attitude and anti-social behaviour that is capable of deeply embarrassing authority figures.
Although her rebellion against social norms is usually constructive, Lisa can be whiny, cruel and self-righteous at times. When she believes herself to be right she won't admit that others could be as well, and will force her beliefs on people. Notably, her increasing sense of moral righteousness regarding her vegetarianism leads her to proselytize, culminating in her spiteful disruption of a "meat-based" barbecue prepared by Homer (an act she comes to rue). At times, Lisa appears to resist certain situations merely for the sake of resisting them, not because of any genuine ideological opposition. She appears to enjoy breaking the norm for its own sake; in one time, she triumphantly declares that she, a girl, would like to join the football team. When it is revealed that there are already girls on the team, she declares her distaste for a sport that would use a pig's skin to make its ball. When it is revealed that the ball is actually synthetic, she is at a loss for words and runs off visibly upset.
Despite her high IQ, Lisa does have typical childhood issues, sometimes requiring adult intervention. She once tricked Homer into allowing her to ride the bus alone, only to become hopelessly lost. After his coworkers Lenny and Carl point out that he allowed his 8 year old daughter to ride a bus by herself, Homer comes to her rescue. Lisa has a Jewish imaginary friend named Rachel Cohen who "just got into Brandeis University." Even with a high intellect, Lisa displays more personality traits of an eight-year old, including obsessing over getting a pony, being addicted to TV, and fighting with Bart. Lisa once got addicted to second hand smoke to maintain an impressive level of ballet competence; Homer tries to prevent the addiction unsuccessfully, and in the end Lisa overcomes the addiction herself through means of "Hello Kitty" nicotine patches. She also displays a surprising amount of skill in driving, especially for her age, sometimes even taking the wheel whenever Homer ended up distracted from driving.
Lisa is an eight year old girl who seems to have a problem with her weight. Sherri and Terri used to make fun of her and her 'big butt', even cruelly call her but size doesn't make sense. Most of Lisa's physical appearances comes from her father's side of the family, so does her stubby fingers which blocks her from her dream of becoming a jazz musician. Lisa is always shown wearing an orange strapless dress and a white pearl necklace. She occasionally wears a pink dress with a dress hat or a hair bow for church and formal activities. She has a 'starfish' like hairstyle which is in the same style as her younger sister, Maggie. Lisa's hairstyle is also a challenge for the animators to draw. Lisa is actually wearing invisible braces from Calvin Klein.
It is mentioned that Lisa has an IQ of 159. She is a high-ranking member of Mensa Springfield. Lisa demonstrates an early intelligence by changing her own diaper as an infant. When unable to attend school due to a teachers' strike, she suffered a sort of "school withdrawal" as she has an emergency box in case of a teacher strike. She begins to panic when she can only think of two synonyms to the word "stop". She constantly wants people to "grade her" as Marge gave her an "A" just to make her stop whining, and invents a perpetual motion machine that Homer describes that it just "keeps going faster and faster". He goes on to chastise her, saying,"In this house, we obey the laws of thermodynamics!" 
Lisa's political convictions are generally leftist and rather liberal. She is a vegetarian, and a supporter of the Free Tibet movement. Lisa yells "Free Tibet!" after winning the school spelling bee. She, like her mom, supported Democrat Mary Bailey over Right-Winged Mr. Burns; the twosome revealed that Mr. Burns was a liar, and Mary Bailey wins in a landslide, the only known supporters being Smithers, Bart, and Homer.
While still supportive of the Christian church she was raised in, Lisa is now a practicing Buddhist following her decision to follow the Noble Eightfold Path. Though apparently not an adherent, she mentions that she considers Wicca "very empowering" 
Lisa turned vegetarian due to ethical reasons. This was also hinted in a flash forward in which we see Lisa as a vegetarian in the future. On Paul McCartney's demand, she has stayed vegetarian still.
Her musical abilities are extensive: she sings with a powerful voice, and has been seen playing the acoustic six-string, electric bass guitar, accordion and piano proficiently. Her greatest love is playing jazz on her baritone saxophone. Her musical inclinations were nurtured by her relationship with the late jazz musician Bleeding Gums Murphy. She most likely inherited her musical ability from Homer, who is also musically inclined.
Lisa had met countless boys during the course of her life. Her dream crush is a heartthrob from local teen magazines, Corey. Lisa admitted to Homer that she liked a boy from school Langdon Alger but she was only joking. Before Trappuccino, Lisa fell in love with an Irish environmental boy named Colin. Colin can play the piano, guitar, trumpet, drums, and the bass guitar. Lisa tells Marge that the best part about him is that he's not imaginary.
Lisa's first boyfriend is a less-than-stellar schoolmate, Nelson Muntz. Lisa once had a crush on him after she found herself strangely attracted to his grungy lifestyle enough to ask him out. After Nelson lied to Lisa about something, she decided to break up with him. However, since then their romantic relationship has been referred to several times throughout the series, most notably in the Season 22 episode, Loan-a Lisa, in which Lisa invests in Nelson's business venture. The episode ends with Nelson taking Lisa rollerblading and the pair holding hands, hinting at a possible future romance.
Ralph Wiggum once had a crush on Lisa after Lisa sent him a Valentine's Day card, but his heart was broken after Lisa admitted on the Krusty the Klown Show that she was not in love with him. They're currently just friends.
Milhouse Van Houten
Of all the boys Lisa encountered, the most desperate and most prominent one was Milhouse Van Houten, who always makes attempts to win Lisa's heart. On one occasion, in order to go on a school trip to Italy, Lisa was forced to learn Italian from Milhouse, who has been to Italy countless times. This nearly caused Lisa to develop a crush on him, until she finds out that Milhouse is with another girl, prompting her to chase Milhouse angrily with a broom. Lisa once tried to bring Milhouse to a school dance in Springfield Elementary but finds out that he's been taken. When Milhouse's parents were reported lost at sea and Milhouse became a loner, Lisa and several other girls became attracted to his new personality. One time when Milhouse fell in love with a new girl named Taffy, Lisa got them to break up, and Lisa kissed him for the first time, and at the same time, she said that she is not sure if she loves him.
Lisa briefly fell in love with a boy, Nick, when meeting him at a lunch she attended with her mom for Valentine's Day. They continued to meet up, but when they met for the last time, Lisa decided she didn't really want to be with him, and he admits that he isn't as good as he says, commonly lying to girls to gain their affection.
Lisa's relationship with her father is labored. The two occasionally got into arguments, but they also have had moments where they really connect. Their relationship has usually been one where Homer ignores Lisa, and Lisa avoids Homer. Lisa seems to be on good terms with her mother,Marge, and the two have a good relationship with each other. Lisa also gets along pretty well with her baby sister, Maggie. Being siblings, Lisa and her brother Bart constantly get into brawls. Their major brawl was after Bart destroys Lisa's centerpiece for a Thanksgiving Dinner. The two once competed against each other in hockey and tried to win over Homer's love. However, the two have teamed up together many times, and they genuinely love each other. This is shown when the two were placed in third grade in the same class (Lisa was moved up from second grade while Bart was moved down). The two got lost in a field trip in Capital City, forcing them to work together to survive. When Milhouse temporarily left Springfield, Bart spent more time with Lisa and the two developed a stronger bond. When Milhouse returned, Bart tried to keep their new bond intact by promising to do her chores and giving her a hug. In one episode, Lisa almosts told two college girls that she thinks Bart is cute, but takes back the statement after remembering that she is talking about her brother.
At the age of 12, Lisa is saved from a house fire by Milhouse, which she later discovers was caused by him. At age 16, she is graduating from Springfield High School two years early and is about to go to Yale on a scholarship provided by Mr. Burns. She is dating Milhouse who she dumps after prom. She becomes furious at Bart for taking her Yale scholarship. She gets back together with Milhouse but Bart saves her and gives her back her scholarship. At age 21, Lisa rejects Milhouse's offer to marry him saying she doesn't intend to ever get married. At age 23, Lisa is at Yale and falls in love with a British man named Hugh Parkfield who she then is about to marry. She is embarrassed by her family and Hugh wants to take her back to England because he hates her family. Lisa dumps him since she would rather have her family. At the age of 30, with Bart needing a digestive tract transplant, she tries to solve the mystery of 'fish logs'. She asks townspeople who tell her the story which takes place when she was still 8. She then finds out that fish logs brought Bart into the hospital in the first place. At age 38, Lisa becomes the first heterosexual female President of the United States. The country is broke and is forced to bring a tax hike but things get worse when Bart interrupts everything. The leaders of the other country's are about to beat her until Bart saves her. To make it up to him, she legalizes the use of cannabis. In her 60s, Lisa is married to Milhouse. She wants to take a poetry class but they are broke and Milhouse spent all the money on the electricity which wasn't enough (though this future was prevented by Bart.) Lisa has also imagined herself married to Ralph Wiggum in the future.
The Simpsons Road Rage
The Simpsons Hit & Run
Lisa is playable in the third level of "The Simpsons: Hit & Run" as she looks for Bart after his disappearance. However, she makes an appearance in the first level in Springfield Elementary School, where Homer has to give her the science project she forgot. By the time the seventh level has come around, Lisa is back in the Simpson house, and tells her father to go out and stock up on supplies. However, by the fourth mission, Lisa is back at the school, where she suggests that Homer goes to Mr Burns to buy nuclear waste, which is the aliens’ weakness. When characters use the Malibu Stacy car in levels four, five, six,and seven Lisa appears in the car.
The Simpsons Game
In "The Simpsons Game", Lisa's powers are playing her saxophone to stun enemies and use the "Hand of Buddha" to pick up and drop big things. This power is later upgraded, enabling her to attack with lightning as well.
Behind the Laughter
Matt Groening first conceived the Simpson family in the lobby of James L. Brooks' office. He had been called in to pitch a series of animated shorts, and had intended to present his Life in Hell series. When he realized that animating Life in Hell would require him to rescind publication rights for his life's work, Groening decided to go in another direction. He hurriedly sketched out his version of a dysfunctional family, and named the characters after various members of his own family, and Lisa is the name of one of his sisters. Lisa then made her debut with the rest of the Simpsons clan on 19 April 1987 in the Tracey Ullman short "Good Night". Nancy Cartwright, originally auditioned for the role of Lisa, but was soon told that her voice would be better suited voicing Bart. Yeardley Smith had initially been asked to audition for the role of Bart but casting director Bonita Pietila believed her voice was too high, so Smith was given the role of Lisa instead. In order to perform the voice, Smith lifts her voice up a little.
In the Tracey Ullman Show shorts, Lisa was more of a "female Bart" and was as equally mischievous as her brother. As the series progressed, Lisa began to develop into a more intelligent and more emotional character with "Krusty Gets Busted" being one of the first episodes where her true intelligence is fully shown. Many episodes focusing on Lisa have an emotional nature, the first one being "Moaning Lisa". The idea for the episode was pitched by James L. Brooks, who had wanted to do an emotional episode where Lisa is sad because the show had done a lot of "jokey episodes".
For a long time, Lisa's saxophone solos were provided by jazz baritone saxophonist Terry Harrington.
In 2001 Lisa received a special "Board of Directors Ongoing Commitment Award" at the Environmental Media Awards. "Lisa the Vegetarian", an episode from the seventh season, won both an Environmental Media Award for "Best Television Episodic Comedy" and a Genesis Award for "Best Television Comedy Series, Ongoing Commitment". Lisa was also listed at number 11 in TV Guide's "Top 50 Greatest Cartoon Characters of All Time." In Japan, the broadcasters of the series found they were able to turn the apparent viewer dislike of the series around by focusing marketing attention on Lisa. Lisa's well-intended but ill-fated struggles to be a voice of reason and a force of good in her family and city struck a chord with the Japanese.