Why the Olsen Twins Won't Be in 'Fuller House'

The reason might surprise you.

Executive producer Bob Boyett told People magazine exactly why the two stars -- who once played Michelle Tanner -- won't be featured.

"Ashley said, 'I have not been in front of a camera since I was 17 and I don't feel comfortable acting,'" he told the magazine. "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.'"

He added that the twins' fashion line also conflicted with filming of the show.

The Olsen twins, 29, were not even 1 years old when the show started filming back in the mid-1980's.