Oscar-winning actress Lupita Nyong’o is back in the headlines, but this time it’s not about a movie or fashion, according to the HuffPost.

Nyong’o, who is busy promoting her new children’s book, got personal on Instagram about how colorism has affected her life. Under a picture of her as a 5-year-old, Nyong’o said she decided to write the book, Sulwe, once she reflected on her upbringing.

“As a little girl reading, I had all of these windows into the lives of people who looked nothing like me, chances to look into their worlds, but I didn't have any mirrors,” she wrote.

Moreover, the book Sulwe “holds up a mirror for dark-skinned children especially, to see themselves reflected immediately, and it is a window for all the others to cherish peering into,” she added.

Nyong’o said society’s preference for lighter skin is prevalent all over the world.

“It's not just a prejudice reserved for places with a largely white population. Throughout the world, even in Kenya, even today, there is a popular sentiment that lighter is brighter,” the actress said. 

Nyong’o was born in Mexico City and raised in her parents’ native country, Kenya.

The 36-year-old has been vocal about colorism in the past. In 2014 she told Glamour that European standards of beauty “plague the entire world.”

She also criticized Grazia UK for featuring an image of her in a cover story that she said strayed away from her naturally Black hair texture.

PopSugar reports the 48-page children’s book will be released on October 15. It focuses on a girl named Sulwe, meaning star in her native language Luo, who goes on a journey to discover her own unique beauty.

“Sulwe has skin the color of midnight,” the book summary reads, according to PopSugar. “She is darker than everyone in her family. She is darker than anyone in her school. Sulwe just wants to be beautiful and bright, like her mother and sister. Then a magical journey in the night sky opens her eyes and changes everything.”