Rushan Abbas’ big sister, Gulshan, has always been her protector. “As a medical doctor, she spent all her life taking care of people. She is the kindest and most caring person I have ever known,” Abbas remembered Monday afternoon, tears starting to soften her eyes. “After my mother passed away 21 years ago, she was like a mother figure to me.” Gulshan means flower garden, and under her protection, Rushan flourished in Xinjiang, the region in Northwest China now hosting a sweeping and systematic oppression some human rights advocates are calling genocide. After Rushan moved to the U.S., Gulshan came...