It's been well documented that Mary-Kate and Ashley Olsen will not join the cast of the new Netflix series 'Fuller House.' The question has remained, "Why?" We now have an answer.

"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 told PEOPLE in this week's cover story. "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.'"

The Olsen twins were younger than a year old when they were cast to play Michelle Tanner on 'Full House.' Despite growing up in front of the camera, appearing on TV, music videos and movies, they have not pursued acting as a career in adulthood.

Neither of them have acted in 12 years. Following the success of their entertainment empire, they launched their own pre-teen clothing line, and they discovered their passion for fashion.

Former co-star John Stamos said he understood their work on their clothing lines, The Row and Elizabeth and James, conflicted with the new series.

"Lori [Loughlin] was talking to me about the twins and said, 'They just won a CFDA [Council of Fashion Designers of America] award.' And I'm like, 'Yeah, that's like winning an Oscar.' It was them and Tom Ford. I get where they're at," he explained.

The People magazine article claims the series will pay homage to the twins by honoring their fashion career, and incorporating into Michelle's storyline. Fuller House debuts Feb. 26 on Netflix.