Kati Marton’s latest book is “True Believer: Stalin’s Last American Spy.”

My daughter gave me a DNA-test kit for Christmas. I dutifully spat in the vial provided and mailed the contents to ancestry.com. A few days ago, I received the shocking result: I am half European Jewish, half Anglo-Irish. This is surprising news, considering my sister recently did a similar test that found her to be of 89 percent European Jewish stock. How could two sisters be of such dramatically different ancestries? My Jewish half made perfect sense: My Hungarian mother and father were both Jewish. When did the Anglo-Irish strand infiltrate my DNA?

It was the second time I was shocked by my identity. At age 30, while interviewing a Hungarian woman rescued by Swedish Holocaust hero Raoul Wallenberg, I learned that my family was not Roman Catholic — as I had been led to believe — but Jewish. More painfully, I learned my grandparents had perished not under the Allies’ bombs — as I had been told — but in the gas chambers of Auschwitz.

This revelation was a source of pride, and relief, too, at being in possession of my family history. It drew me back to the homeland I left as a small child. Hungary’s violent, hate-filled history became the subject of several of my books. For my parents, it was a different matter. They were part of a generation of secret-keepers, with much to forget. They had twice suffered as a result of their identity. First, as Jews in anti-Semitic Hungary, where they barely survived the Arrow Cross reign of terror. Then, in the 1950s, they were labeled Enemies of the People (a label invented not by Stephen K. Bannon or Donald Trump, but by Joseph Stalin) and jailed as “American spies” for the crime of being brave reporters who supported the West during the Cold War. For my mother and father, identity was a minefield, and America was their last chance.

Now, thanks to ancestry.com, my own identity is again shadowed. Was my beloved father not my biological father? If not, who was? Searching dusty files of letters crisp with age, I found a copy of a letter (the original is in the Budapest secret police archives) that my father had written my mother from jail. “Your only goal must be to leave with the children,” he instructs my mother, unaware that she was by then an inmate in the same maximum-security prison in Budapest. “Mathew Crosse should come and marry you. Your responsibility for the children and for yourself is to leave me.” Heartbreakingly brave words, but who is this Mathew Crosse? Might he be the source of my 50 percent Anglo-Irish blood? Should I search for him? If I were to find an Englishman who visited Budapest in the late 1940s — or his offspring — what then?

All day I walked around in a fog of disbelief. I felt unmoored. But my family stayed calmly in character. My sister cheered that we had cause to celebrate St. Patrick’s Day on Friday. My analytical son and daughter suggested we do a DNA redo, using a different company. True Americans — Anglo-Irish Canadian in addition to Hungarian — they knew who their grandfather was: Papa, who barely survived the fevered identity politics of his Hungarian youth but taught all of us to ski and play tennis (though he failed miserably at teaching us to fence). His proudest achievement was not his career of stellar journalism but leading us to sanctuary in the United States.

In a couple of weeks, my family will celebrate the day a refugee transport brought my parents, my sister and me — along with hundreds of other Hungarians — to Camp Kilmer, N.J., in 1957. I was the youngest refu­gee, and it was my birthday. The Marine who “processed” me noticed this and produced the gift of a silver dollar. I still have it.

(YouTube/Peter Wall Institute for Advanced Studies)

My ancestry.com shock lifted the next morning. Regardless of the accuracy of this test, I know who I am. Family is about more than DNA. Identity used as a weapon of exclusion leads to hate, and once before it led to ashes gusting from Europe’s factories of death.

Why search for clues to an Englishman who may or may not be my biological father? Why redo a DNA test? I know who my father was, and I know who I am. I am Papa’s American daughter.

Of far greater concern than my own, is our country’s DNA today. Would a little girl arriving after an even more perilous journey still be greeted with a smile and a silver dollar?