Actress Mary-Kate Olsen has hit out at people who question her about the Olsen twins’ fortune — insisting her personal wealth is of no concern to the outside world, reports.

The 21-year-old began acting as a baby, appearing in the 1980s show Full House alongside twin sister Ashley.

And the pair, who have gone on to launch a hugely lucrative merchandising empire, are estimated to be worth more than $100 million US.

But when questioned on her position as a wealthy young woman, Mary-Kate insists it shouldn’t be of interest to anyone.

“It’s nobody’s business if I am or I’m not (rich),” she told Us magazine.

Olsen doubts she would have considered a career in show business had she not started out as a youngster, insisting she is only acting now because it is all she has ever known.

“I grew up in it,” she said. “It wasn’t something that I aspired to. It’s just something I knew. For me, I just worked. I had a job. I’ve had a job for 21 years.”