The 30-year-old UK X Factor judge said that as the only black girl in her class, she felt like an outsider.
“There’s so much peer pressure growing up, I had an identity crisis,” she told Now magazine.
“I went to a predominantly white school and I was the only black girl.
“I can remember thinking, ‘I don’t want to be as dark as I am - I want to be a little fairer. I didn’t want to be me.”
But it was her Destiny’s Child band mate Beyonce’s mum Tina Knowles who helped her to find peace with herself.
“Tina sat me in front of the mirror and said, ‘Girl, look at how pretty you are’.
“She made me feel comfortable in my own skin.”