When Phoebe was 14, her mom killed herself, her stepdad went to prison, and she was living with a guy named Cindy who talks to his hand (according to her). She later found out that her birthmom, which is also named Phoebe, lives in Mauntok. She got to talk to her mom and this is part of their conversation:
Phoebe: I-I mean I, well I think I can figure it out. I guess y'know I was born, and everyone started lying their asses off!
Phoebe's Mom: Well, the-the three of us we were, kind of umm, a couple.
Phoebe: I don’t even know how that would work!
Phoebe's Mom: Well, we were...
Phoebe: (interrupting) I’m not asking!
Phoebe's Mom: Well, any how, some how I got pregnant, and, and I was scared. I was stupid and sellfish, and I was 18 years old. I mean, you remember what it’s like to be eighteen years old?
Phoebe: Yeah. Let’s see, my had Mom killed herself, and my Dad had run off, and I was living in a Gremlin with a guy named Cindy who talked to his hand.
Phoebe's Mom: Well, I’m so sorry. I thought I was leaving you with the best parents in the world, I didn’t even hear about your Mom and Dad til a couple of years ago, and by then you were already grown up. I don’t know, you’re here, and I would, I would really, I would like to get to know you.
Phoebe: Yeah, well, everybody does! I’m a really cool person. And y'know you had 29 years to find that out, but you didn’t even try! Y'know what, you walked out on me, and I’m just, I’m gonna do the same thing to you.
Phoebe has a twin sister named Ursula. Ursula and Phoebe never get along. Frank Jr. is also Phoebe's step-brother.
How she got in the group? Well, Monica was her roomate. She later left because she needed to be "in a world where she can spill". Now Phoebe is sharing an apartment with a girl named Debbie(we never really saw Debbie on any of the episodes). Phoebe also shared an apartment with Rachel after Rachel moved out of Monica and Chandler's apartment. Phoebe works as a missuse. Also, Phoebe entertains people at Central Perk, where she sings.
Phoebe is most certainly the weirdest one in the group. I mean she has a "spirit of an old lady living in her ceiling". She's a nature lover and is against killing trees and animals. That's why she's vegetarian. She also predicts what happened. When the group was in London she knows that Monica had sex (although Monica denied it) and Joey ate meat. According to Rach and Mon, she is flaky. She doesn't believe in evolution or gravity. Being weird is probably how she's funny and that's why we love her.