[Entropy999]

i have younger identical twin sisters (50 years old). One of them seems to be a chronic liar and a hypochondriac. She lies to make herself look better, to get out of doing things, and lies about herself by saying things have happened to her that actually happened to other family members. She works at the same place as her twin sister and lies to take credit for her work. When asked what she did over the summer she lied and said she did something that I had done. Our older sister was just diagnosed with ovarian cancer and she immediately ran to the ER with the same symptoms to get completely checked then led people to believe she has cancer. Her twin sister had an ovarian cyst and she told people at work she had the cyst. She has been complaining of illnesses for years and running to the ER with nothing ever wrong with her. Our parents are very old and no one in the family wants a confrontation so no one calls her on her on her lying. Up until now most have believed her except her twin sister because she has grown up close to her. They don't get along well and are competitive. Why does my sister lie constantly ? It's become worse since the cancer diagnosis of out other sister. The lies are easily proved but she doesn't seem to care. Is it because no one has ever help her accountable she thinks we are too clueless to know? Is this a mental illness? Thanks for any advice.

[Tauren]

Yes it's a mental illness. https://en.wikipedia.org/wiki/Pathological_lying

If it helps, try to remember that she can't control it.

[starfruit504]

Have you considered BPD?

Pathological lying is not a mental illness. It doesn't appear as a diagnosis in the DSM. This article on Psych Central argues it could be a symptom of something larger, like a personality disorder.

[MissFiona]

Seems to be some type of attention seeking strategy where she is running to the Dr. to be checked out or enacting situations or illnesses that are actually happening to people in her surroundings. To me it reads as though she knows there is something wrong but she can't work out what it is so the behaviours she brings out may in fact be some form of cry for help by someone who cannot express themselves so it's just easier to copy others and lie. You mention it's become worse since her twin was diagnosed and that she doesn't seem to care if she is caught in a lie. This may well be because she is looking to someone else to take control over a situation she has no control over within herself. Let alone understands. Nobody wants to confront her over her lying. To me it reads as though there is no need for confrontation about her lying as that will achieve nothing, but perhaps it is well overdue that she is gently guided to a mental health professional.