Selma adopted Ling in Beijing, China after discovering that she had reached menopause. She lied about being married to Homer Simpson, in order to fool the local authorities into thinking that Ling would be part of a traditional family as opposed to a single mother. Though she and Jacqueline Bouvier have only been seen once together, Jacqueline is her adopted grandmother. It is later revealed in Changing of the Guardian that Selma and Patty push her to her limit in numerous hobbies and fail to praise her. It’s unknown who her biological parents are nor is it known if they’re alive or deceased. She also has diabetes, which she was more than likely born with.
Ling has a weird habit of squeezing Homer’s eyeballs, which he doesn’t seem to mind, even though it would hurt.
In her first appearance in Goo Goo Gai Pan, she only made a few appearances making baby giggles and her only actual word in the series was "mama". During her other three appearances, she did not talk. She has a laugh similar to Selma.
She appears slightly older by "Changing of the Guardian", walking, exhibiting manual dexterity, and even performing gymnastics. She also seems able to speak in complete sentences, saying "Help me!" to Marge.
Note: All of Ling's major appearances are in bold.
In Changing of the Guardian, Ling is shown to have grown a couple of years older since her first appearance in Goo Goo Gai Pan, although Maggie, who is about the same age as Ling, has not, which makes her one of the few characters who has aged in the series.
She is Bart, Lisa and Maggie's so far only known cousin, not including Jessica Simpson since Lisa most likely made a joke about her being her "cousin."