"We changed our light bulbs and we have hybrids," says Lisa Kudrow, adding that her husband is in the market for a new electric car. The producer of NBC's genealogy series "Who Do You Think You Are?" is excited about the third season's lineup of celebrities investigating their ancestries, which begins with Martin Sheen in the Feb. 3 debut.


"I don't want to ruin it," she prefaces, hinting at a coincidence involving a key document "that has somehow been preserved for hundreds of years," she says of the Sheen story. The eleven subsequent episodes focus on Marisa Tomei, Blair Underwood, Reba McEntire, Rita Wilson, Edie Falco, Rob Lowe, Rashida Jones, Jason Sudeikis, Paula Deen and Helen Hunt, whose story Kudrow considers especially moving. "She really didn't know anything about her father's side. His mother died when he was five years old, killed by a drunk driver. She was expecting an Eastern European Jewish story with some tragedy in it, but it was a total surprise, a huge shock. She ends up in tears."


Thinking ahead to future "Who Do You Think You Are?" seasons, Kudrow acknowledges having approached her "Friends" co-stars about participating. "We have asked. Schedules haven't worked out or someone doesn't want to do it. It's not for everybody. It can be extremely emotional. Not everyone gets a Brooke Shields" kind of reveal, she says, referencing the episode in the first season in which Shields discovered her royal roots.


It's also far easier to trace the lineage of the rich, who have traditionally paid attention to ancestry and kept good records, Kudrow notes. Poor immigrants from Ireland and Italy are tougher to research, and Eastern European Jews are especially difficult, because many families didn't use surnames until the 19th century, and records that did exist, many kept in synagogues, were destroyed in the Holocaust. "We lucked out with Gwyneth Paltrow last season," she says, suspecting that the records were better in her family's case "because they were rabbis."


For Kudrow, working on the show is a labor of love, "more than the acting or writing or any of it," she says, though she's not giving up on-camera work.  She'll be back this summer with more "Web Therapy" episodes on Showtime.


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Lisa Kudrow: Light bulbs and hybrids
Kudrow helps a wide variety of big stars trace their ancestries on 'Who Do You Think You Are?'