For the first time in its history, the colonial government of Hong Kong began to turn Chinese away from its bursting border. The defeated Nationalists who had fled to Taiwan earlier eyed every new arrival from the mainland as a possible Communist infiltrator. Those who reached the United States, the most desired and difficult port of entry, were greeted by immigration officials trained to enforce highly restrictive laws against Asian immigrants. Legislators raised alarms about an enemy Fifth Column even as they feigned humanitarian concerns; the F.B.I. interrogated immigrants and conducted raids on homes and businesses; many immigrants were detained on Ellis Island for varying lengths of time before they were released — or deported.This all played out during McCarthy-era hysteria about Chinese Communism. My parents — who met in New York City — had each entered the country legally. But when their visas expired, they became undocumented, stateless refugees, and in 1955 were told they would be deported. Ultimately, immigration officials relented, citing the “extremeley unusual hardship” it would impose on their children — my two brothers and me, still all in diapers and American citizens by birthright. Even in those years of Cold War paranoia, it was unthinkably inhumane to separate parents from children.Learning my mother’s stories for the first time, I began to understand why so many of the refugees and migrants chose not to tell their children about their exodus from Shanghai. Why recall trauma and hardship when, after finding places of refuge, they could focus on encouraging their children to reach their full potential? They themselves had not had that opportunity. Even a cursory look at immigrants in America shows that a disproportionate number of their offspring pay forward their parents’ sacrifices. The Shanghai exodus produced Maya Lin, the architect, Elaine Chao, the secretary of transportation, the Nobel laureate physicist Steven Chu and the novelist Amy Tan. Other migrations have brought the nation talents as varied as the former secretary of state Colin Powell, the writer Edwidge Danticat, the guitarist Carlos Santana, the actress Lupita Nyong’o and too many more to name.My mother did not live to see herself in my book, but her secrets enabled me to see today’s migration crises through the eyes of a frightened child. It should not take another seven decades to grasp why present-day migrants risk all to face tear gas at a border, to brave rough seas in rubber rafts, to crowd into the next boat, plane, train or bus out of fear that it may be the last one out. Or for the nation to realize that these refugees and migrants give so much more to the communities that welcome them than they will ever take away.Helen Zia is the author of several books, including the forthcoming “Last Boat Out of Shanghai: The Epic Story of the Chinese Who Fled Mao’s Revolution.”Follow The New York Times Opinion section on Facebook, Twitter (@NYTopinion) and Instagram.