Novelist Khaled Hosseini has announced that his daughter has come out as transgender.

Hosseini, author of the bestselling 2003 novel The Kite Runner, shared the news on Instagram, in a post accompanied by a black-and-white photo of his daughter.

“Yesterday, my twenty-one year old daughter Haris came out to the world as transgender,” Hosseini wrote. “I have known about Haris’ journey since last year and I’ve watched her navigate some very trying personal times. Transitioning is such a complicated undertaking—emotionally, physically, socially, psychologically—but Haris has met each challenge with grace, patience, and wisdom.”

Many of Hosseini’s followers reacted to the news with statements of support, with readers commenting, “She is lucky to have you as her father” and “Congrats to Haris on living her truth and to you for supporting your daughter in her journey.”

“As a father, I have never been prouder of her,” Hosseini wrote. “I am delighted to now have not one but two beautiful daughters. Most of all, I am inspired by Haris’ fearlessness, her courage to share with the world her true self… I love my daughter. I will be by her side every step of the way, as will our family. We stand behind her. It’s a privilege to watch her enter the world as the beautiful, wise, and brilliant woman that she is. May God bless her.”

Michael Schaub, a journalist and regular contributor to NPR, lives near Austin, Texas.