CYBILL SHEPHERD’s twins may be “grown up” but OY VEY!

The star’s 22-year-old daughter Ariel Shepherd-Oppenheim just came out publicly as a lesbian, and her twin brother Zack was recently ordered to attend Alcoholics Anonymous after being caught stealing from fellow passengers aboard a United Airlines flight!

Zack was arrested at Philadelphia International Airport on Jan. 12 when cops caught him with a Canon digital camera and cash he had swiped from carry-on luggage during a flight from San Francisco.

He had rifled through the bags of two sleeping travelers during the flight, two witnesses told authorities.

Zack – a student at the University of Pennsylvania – was charged with theft, unlawful taking and receiving stolen property. On June 4, a Philadelphia municipal judge ordered him to attend 24 AA meetings and pay $55 in restitution.

Meanwhile, his twin sister Ariel stepped out in public with her new girlfriend at the June 5 GLAAD Media Awards in San Francisco. Cybill – who played a lesbian for three seasons on Showtime’s The L Word – was given a commendation by the gay rights group.

Ariel makes lesbian daughter No. 2 for the 60-year-old former Moonlighting beauty.

Cybill’s older daughter, Clementine Ford, 30, came out last year.

Cybill, by all accounts, has no problems with her daughters’ gay lifestyles.

"Cybill’s always been a huge supporter of gay people," said a source close to the actress.

Clementine and Ariel presented Cybill with GLAAD’s annual Golden Gate Award, which is given each year to an individual who helps raise visibility for the gay community.