BERLIN—Düzen Tekkal and her family had put on their best clothes for the naturalization ceremony. But when her father expressed his joy at becoming German, the presiding civil servant said, “You are not German—you only have citizenship.”
Ms. Tekkal was 8 years old at the time, the daughter of Yazidi immigrants from Turkey. Now she is an author, the head of a charity and a contributor to a social-media movement known as #MeTwo—a play on the #MeToo controversy and the split identities of many immigrants—that is raising awareness...