MELISSA BLOCK, HOST:

It started as a whim, an afterthought, really - just a bit of spit into a plastic vial. But for writer Dani Shapiro, what she came to learn from that DNA test would up-end everything she thought she knew about her identity and her family's history. As she would learn, her beloved late father, Paul Shapiro, was not her biological father, and the Orthodox Jewish heritage that she so prized was not her own. Dani Shapiro unravels her family's story and the secrets it held in her new memoir, titled "Inheritance."

Dani, welcome to the program.

DANI SHAPIRO: Thanks, Melissa. It's great to be with you.

BLOCK: You find this out several years ago. You took the DNA test, as we say, as a fluke. You compare results with the woman who you thought was your half-sister, and you find out that you, in fact, are not siblings. You do not share a father. What was your reaction? Were you - was this traumatic? How did you feel?

SHAPIRO: I initially didn't believe it. It just seemed an impossibility. I thought that the DNA testing company must have gotten it wrong. I had my husband call them. So it really was kind of a slow seeping in of this is the case. This has always been the case. And it was like a reckoning.

BLOCK: And as you start unpacking this, you think back to something that your mother had told you 30 years before. She had dropped a really big clue. She said, you were conceived in Philadelphia. It's not a pretty story. She talked about having infertility trouble, that they'd gone to what she called a world-famous institute in Philadelphia for artificial insemination. And you had also heard from your - the woman you thought was your half-sister - that they used to mix sperm in those days. This was all something you had heard long before but had not fully digested, it sounds like.

SHAPIRO: Well, I had dismissed it because my mother made it very clear to me that it was my father's sperm used in the procedure. And when I went back to her after my half-sister said you might want to look into this because they mixed sperm, my mother said to me, can you imagine such a thing? My father was an Orthodox Jew. She said, can you imagine that your father ever would have agreed to do something like that? It would have meant that he wouldn't have known whether his child was Jewish. And I completely accepted that because I couldn't imagine that that would've been something that my father would've been on board for.

BLOCK: The main moral question that it seems like you're struggling with throughout this book is the question of whether your parents knew that your father wasn't actually your biological father. Were they aware of that? Did they dismiss it? Or did they not know at all? What did you, in the end, decide about that? Did they know?

SHAPIRO: Yeah. I mean, that really was the heart of the whole journey of this discovery for me. It was much more important to me than knowing or meeting my biological father. It was, who were we to each other, my parents and me? What did they know, and did they keep this a secret from me my whole life? And I began, really, with a feeling of they must have not known. We were all in the dark. The institute must have fooled them. I had this whole kind of - it was much more comfortable for me to feel that we were all in the dark together.

But no one got on-board for the idea of your parents didn't know. Not one single person I talked to - not experts, not people who knew my parents - no one believed that they didn't know. And so there was this process by which I came to understand, first of all, a lot about the history of reproductive medicine. At that time, infertility, male infertility in particular, was so shameful. And when they chose to have a child in this way, with donor insemination, it was a huge secret.

There was a practice at that time of mixing donor sperm with the intended father's sperm. It was meant to allow the couple to just really have a kind of plausible denial that this had happened. I believe that from the time my mother got pregnant with me, she decided that I was my father's child. My father, though, I think is a different story I think that he - and I'll never know, but I do think that he knew that I - that he wasn't my biological father.

BLOCK: We should explain, too, that you look very different from your father and his side of the family. And you would hear very often, you don't look Jewish.

SHAPIRO: Yeah. I was very fair, pale-skinned, blue eyes. It really was the story of my life - that literally every day, someone or another would say, you don't look Jewish, or you can't possibly be Jewish.

BLOCK: At the same time, when you talked to an old friend of your mother's, she says your father is still your father - that nothing in that has changed, really.

SHAPIRO: When she first said that to me, it was within 24 hours of my having made this discovery about my dad, and I could not hear that. I felt betrayed. I felt lied to. And yet, my father loved me into being. My father is who raised me, and so much of who I am is the result of our shared time together. And, you know, at the time, everyone was told by doctors - and doctors were god in the early 1960s - the child will never know, and what we don't know won't hurt us. And the idea of a future in which you could spit into a plastic vial and send it away through the mail would have been completely the stuff of science fiction.

BLOCK: You end up very quickly - within 36 hours and some very careful computer searches - tracing back to the sperm donor who is your biological father. You call him Dr. Benjamin Walden. That's not his real name. And you actually find a video of him giving a speech. What did you see when you were watching that video?

SHAPIRO: I saw myself in a 78-year-old retired physician giving a speech. He was gesturing the way that I gesture. I looked like him, and I had his coloring and his features. But it was much more than that - it was a quality that I recognized as being a quality of my own.

BLOCK: You describe in the book the process of reaching out to your biological father and, in the end, meeting him and his family. What has that been like for you?

SHAPIRO: In a way, it has contributed to a sense of wholeness. I feel very, very fortunate that that was able to happen. It's helped me to, you know, have the experience of sitting with and meeting and to some degree getting to know the man who is my biological father.

BLOCK: You write toward the end of your book about meeting with a rabbi, Rabbi David Wolpe, who quotes to you from a poem by Elizabeth Barrett Browning. You've been talking with him about otherness. And I wonder if you could read the part of that poem that he quotes to you.

SHAPIRO: Yes. (Reading) God answers sharp and sudden on some prayers and thrusts the thing we have prayed for in our face, a gauntlet with a gift in it.

BLOCK: And what did you take from that?

SHAPIRO: That really reframed, in a way, my experience - is that for sure it was a gauntlet but that there was this very powerful gift in it - that I was seeing and understanding the truth of myself in a way that I had never been able to before.

BLOCK: That's Dani Shapiro. Her book is "Inheritance: A Memoir Of Genealogy, Paternity, And Love."

Dani, thanks so much.

SHAPIRO: Thank you.