In Mischling, twin girls face the experiments of Josef Mengele at Auschwitz.

How did you get interested in writing about the Mengele experiments on twins?

A book called Children of the Flames was my introduction to the subject. I was interested in how those experiments came between certain twins and drew others closer together.

Did you have concerns about turning this piece of history into a novel?

Absolutely! I found Children of the Flames when I was 16, and I thought, someday, maybe, I could tell this story. I spent years thinking somebody else would snatch it up. But I’m glad that it took this long to write. If I had been swifter about it, and less plagued by doubt, it would have been a very different book.

One of the things that impressed me about the book is that you don’t let Mengele, this larger-than-life figure, run away with the novel.

One of the things that stalled the process was trying to figure out how to handle that character. Do you make him a clown? To make him a hole in the story meant more than to try an explore a monster you can’t possibly understand, a man who could carry a child on his back, carting him around one day, and then would personally usher him to the gas chambers the very next day. There’s no way you can reach an understanding of that.

You make the bold choice to extend the novel well beyond the point where the camps are closed.

One of the first books I read on the Holocaust was The Truce by Primo Levi. He made this circuitous journey back home from the camps, with these odd, comic little moments about some of the people he met along the way, interspersed with the tragedy. It made me wonder how you deal with a world that has essentially ended for you. I felt like the book couldn’t end with liberation; it wouldn’t say enough about the sort of future that these children were facing.

There are a number of characters based on real-life people in the novel. Which of those did you find most interesting?

The book became so populous. I was very surprised! Dr. Gisella Pearl, who in part inspired Miri, is hard for me to put aside even now. Zvi Spiegel, who inspired the Twins’ Father. There are so many characters I would have liked to spend more time with. A lot of the twins were composites, not directly inspired by Eva Kor and Miriam Zeiger, but those two figures were very important to me. I would hope the novel stands as a sort of tribute to them.

Could you talk about the title of the novel?

It’s a German term that suggests mixed blood. It has a strangely musical quality, with a kind of lilt. It’s terrifying because it’s almost charming in sound. I saw its use in the narrative as showing that trauma might change a person, especially a really young person, in a primal, blood-level way, making a person feel like a hybrid of many things: child and adult, innocent and world-weary, dead and alive.