Meredith has two kids. Her son is with her. Her daughter ('the good one') is with her ex-husband. In the episode "Take our Daughters to Work Day," she brings her son, who has been suspended from school. He flings candies at Michael while he's trying to talk to Pam, and he also addresses Dwight as Mister Poop. He shows a lot of interest when Pam offers to show him how to shred papers. Meredith's alcoholism sometimes affects her job performance. In one episode she passes out with her head on her desk. In another, after a party in the office, she combines her drinking with her crush on Michael by appearing topless in front of him in Michael's office after everyone else has left. Michael becomes uneasy, says good night, and leaves. Meredith apparently also has some kinky sexual interests based on the scene in the episode when Michael tells the girls that Jan likes some unusual, even "dangerous" sexual practices. Pam says "Normal women don't do those things," and the expression on Meredith's face at this point seems to indicate that she thinks Pam has led a sheltered life.
Meredith is allergic to dairy.
She doesn't have a uterus (she had a hysterectomy) but she still has a vagina.
Meredith's alcoholism is first revealed in Christmas Party.