The premiere episode of Fuller House features the entire cast from the original series – minus two.
Mary-Kate and Ashley Olsen, who portrayed Michelle Tanner on Full House from 1987–95 beginning when they were 9 months old, are not returning to the spin-off series for a couple of reasons.
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"Ashley said, 'I have not been in front of a camera since I was 17, and I don't feel comfortable acting,' " executive producer Bob Boyett tells PEOPLE. "Mary-Kate said, It would have to be me because Ash doesn't want to do it. But the timing is so bad for us."
Production conflicted with the 29-year-old twins' schedule as designers of The Row and Elizabeth and James, Boyett adds. The show does play upon their real-life career, explaining that Michelle is absent from the first episode's family reunion because she's busy running her fashion empire in New York.
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Despite some initial disappointment, the cast tells PEOPLE they understand the twins' reluctance to join the show. (PEOPLE's requests for comment from the Olsens were not returned.)
"Lori [Loughlin] was talking to me about the twins and said, 'They just won a CFDA award.' And I'm like, 'Yeah, that's like winning an Oscar.' It was them and Tom Ford. I get where they're at," John Stamos tells PEOPLE.
There's also geography (the Los Angeles-based cast has stayed very close over the years; the Olsens are in New York City much more often) and the age difference.
"They're family members," Dave Coulier tells PEOPLE. "But I think they have a different perspective. When we get together and we reminisce, they were babies [at the time]. So they don't share those same memories. I can't really speak for them but I would understand why they don't have the same sentiments that we all do."
Fuller House premieres Friday on Netflix.