We see Regina's dad very, very briefly, sobbing as his daughter poses in her barely-there Halloween costume.
Her mom, on the other hand, is a constant presence, desperate to be "just one of the girls." She's not interested in being a mother, she's interested in being in The Plastics, and she sucks up to her own daughter like she's Bethany, a.k.a. the girl who thought it was awesome when Regina punched her in the face one time.
Regina's not impressed with her mom's offers of mocktails and "fashionable" sweatsuits. In fact, she treats her mom and her quest for coolness like an embarrassing nuisance and…her mom just takes itL
MRS. GEORGE: Just want you to know, if you need anything, don't be shy, okay? There are no rules in this house. I'm not like a regular mom. I'm a cool mom. Right, Regina?
REGINA: Please stop talking.
MRS. GEORGE: Okay.
As the most popular girl in school, Regina doesn't need any more friends. She needs a mom, someone who can show her how to make good decisions and instill some solid values in her that don't involve breast implants or sports cars. Regina may put the "mean" in Mean Girls, but Mrs. George's superficial, lackluster parenting seems to have put the mean in Regina.