Baby, baby, baby … uh oh. A California woman is claiming that the Biebs is her baby daddy, according to a Star magazine exclusive. Mariah Yeater, 20, has filed a lawsuit demanding the pop star take a paternity test “to scientifically confirm” that he is the father of her 3-month-old boy. Yeater maintains she had sex with Justin Bieber backstage at one of his concerts when she was 19 and he was 17 (there’s no mention about the Biebs being a minor when the alleged incident occurred). She reportedly filed the papers in late October asking the court for Bieber “to provide adequate support for my baby.” Bieber’s reps have said the allegation is false. Meanwhile, he recently adopted a puppy with his girlfriend Selena Gomez.