Selma Bouvier Terwilliger Hutz McClure Simpson is the 42-year-old twin sister of Patty Bouvier, and older sister of Marge Simpson. She was born on June 11,1947. She does many things together with her sister; they live together, they both work on the DMV, their favorite TV show is "MacGyver," they're both chain-smokers and they both think Marge married beneath her family's wishes mainly because they liked for her to be with Artie Ziff, who would've made a good husband for her, unlike Homer, whom was beneath their family's contempt because he was a moron who would hurt her. However, Selma has shown more kindness to him, unlike Patty who still shows nothing, but hatred towards Homer.
She also longed for a baby and a family of her own. Unable to find companionship in a husband, Selma has also sought to have children. At one point she was considering using a sperm donor. After babysitting Bart and Lisa for a day at Duff Gardens, she realized that although she wanted someone to love, she was not ready to have children and wound up adopting Jub-Jub, her Aunt Gladis' pet iguana. Finally, in "Goo Goo Gai Pan", a very menopausal Selma adopted a Chinese baby, Ling Bouvier. During the adoption process, Selma pretended to be married to Homer, since the Chinese government only allows children to be adopted by married couples. When the fraud was exposed, Selma managed to keep the baby, as a Chinese dignitary (voiced by Lucy Liu) became very sympathetic towards her and revealed to been raised by a single parent.
Relationships with other men:
Her first husband was Sideshow Bob Terwilliger, who would have blown her up had her nephew Bart not stopped him. He deduced that, because of a childhood accident which robbed her of her sense of taste and smell, she would not smell a gas leak. When she watched TV and lit her cigarette, the explosion would have killed her. Bart got there just in time.
She had dated Hans Moleman, Moe Syzslak and Barney Gumble, pity date.
Her next husband was inept trial lawyer, Lionel Hutz.
After that she had a very public marriage to actor Troy McClure, who used her to dissuade the rumors about his personal life and help his sagging career. When she realized the marriage was a sham, she and Jub-Jub left him.
Later, she married Abraham Simpson, Homer's father. For a brief period of time, they lived together, but they realized that the marriage would not work out right. This was mainly due to the fact, Homer and Patty were both against their relationship as from the start.
Although she had refused to marry Apu considering that his name would be too long of an addition to hers, she had slept with him before, especially after Homer and Marge's second wedding.
Selma's relationship to the Simpson family:
Despite sharing the same hope with Patty in wanting Marge to divorce Homer and marry Artie, Selma has shown that she's making a sincere attempt to like him, mainly out of respect for both Marge and Homer. She was also flattered to see that his loyalty to his family has proven more unwaivering than what she has expected from him since she expected him to care for his own interest. Despite Homer's loyalty to Marge, Patty still refuses to stop pointing out his infedelites of anger and resentment towards him. Unlike her, Selma knows when to back off of Marge and accept Homer.
However, Selma once took the Simpson children on a disastrous trip to the Duff Gardens theme park in the episode "Selma's Choice." She is unable to control the children: Bart manhandles several animatronic characters and Lisa goes on a psychedelic trip after drinking "water" from an It's a Small World-like boat ride. She was later swimming in the Fermentarium and exclaiming "I am the lizard queen!" After that, however, Selma returned home with the children and asked Homer how he does it, referring to raising children, implying that she's far more capable of overcoming her dislike of him than Patty. When she told him that she just couldn't cut it today, Homer comforted her, showing that he does care for her as his sister-in-law. As noted above, he's also willing to help her adopt a baby, further highlighting their tolerance for each other. He also holds high opinion for Selma, which is also shown in Treehouse of Horror XIV in which he sacrifices Patty instead of her to save Marge. While this scene is non-canon, it gives insight to Homer's true opinion of her, compared to Patty.