Tara Westover grew up preparing for the End of Days in rural Idaho with radical survivalist Mormon parents. She didn’t get a birth certificate until she was nine and had no medical records because her father did not believe in doctors. She and her six older siblings worked in her father’s junkyard. As she grew older, her father’s beliefs became more extreme and one of her brothers grew violent. At 17, she decided to educate herself as a means of escape. Within 10 years she had earned a PhD in intellectual history and political thought from Cambridge but was estranged from her parents and half of her siblings. Now 31 and still living in Cambridge, she has written a powerful memoir, Educated, about the transformative power of education and the price she had to pay for it.

Can you describe your childhood?

It was very isolated. Because I didn’t go to school I didn’t have friends in the way other people do. The only people I knew were the children of families like ours, who were home-schooled, anti-doctor, and we didn’t see them that often. I think I was 13 when I first went to another child’s house who went to school. I didn’t ask her back because she teased me about not knowing what a fraction was.

Do you have any warm memories from growing up?

I have a lot, actually. The mountain where we lived was a beautiful place and the scrapyard was fun in many ways; it was exotic. My mother was a midwife and a herbalist so we would go on these long walks, looking for yarrow or rosehips or whatever she needed to make her tinctures. I also have a lot of good memories of breaking horses with my brother Shawn before he became violent. There was a dramatic moment when I was on a runaway horse and he actually saved my life heroically.

As you grew older Shawn began to bully and abuse you. He pulled you around by your hair, broke your wrist, flushed your head in the toilet, killed the family dog and threatened to kill you, too. How did this begin?

When I was 15 and he found me smudging my eyes with my sister’s mascara. He couldn’t stand seeing me grow up to be a woman. He regularly called me a whore and a slut. Whenever he hurt me he was always really apologetic afterwards. He tried to say it was just a game that he hadn’t meant to harm me, and it was always my brother’s version of events rather than mine that I wrote down in my journals. I made myself believe it was true.

How could your parents have turned a blind eye to what was going on?

That’s the biggest question of my life. I was reluctant to speak to my parents about it for a long time because I didn’t want to acknowledge the unthinkable – that they already knew but had done nothing about it.

Was that what finally led to the rift between you and your family?

Yes. What broke us was not me going to college against my father’s will or even leaving home to go to Cambridge. It was me speaking openly about my brother Shawn being violent and abusive to me. My parents couldn’t deal with that so they turned the other way and made me look like the bad person. In families like mine there is no crime worse than telling the truth.

Can you see yourself becoming reconciled with them?

I will always hope that we might be reconciled, and I hope for the sake of my brother’s wife and family that he’s mellowed and changed. But while I’ll always watch for signs that the family culture has shifted away from secrets and enabling, I don’t wait for them.

Do you miss your family?

I miss them every day, but I can also feel comfortable with my decision not to have them in my life.

Would you recommend going to college or university with no prior experience of school?

No! Not at all. I felt like the only dancer on stage who had missed rehearsal. And I made some excruciating missteps, like the time I was in a European history lecture and I asked what the Holocaust was. No one believed I didn’t know. They all thought I was some kind of racist. But then again, after years of knowing virtually nothing at all I found learning so exciting. I piled up books and read late into the night. Sometimes I barely slept.

How do you feel about this very personal book being published?

I am already in pre-emptive therapy with a brand new therapist. You probably think I’m joking but I’m not. I told him, “I’m fine right now but in two weeks when this book comes out I might be freaking out.”

You say “brand new” – have you been in therapy before?

I had a mental breakdown while doing my PhD at Cambridge, soon after I cut off contact with my parents, and I started seeing the university counsellor, one of the best decisions I ever made. There’s something very nourishing in setting aside an hour a week to talk. The act of admitting that I needed something I couldn’t provide for myself was immensely helpful.

You write with the flair of a novelist. How did you learn that?

Everything I wrote at the beginning was awful. Then I became obsessed with the New Yorker fiction podcast.You can hear these wonderful things like Margaret Atwood reading a Mavis Gallant story and then she and Deborah Treisman, the New Yorker fiction editor, will discuss why it works. They’ll bring up all these weird little things that writers do that make it much easier to say – “Yeah, I can do that too”.

How do you feel about Mormonism?

I feel very grateful to the church and to [the Mormon] Brigham Young University, where I first went to college, but I can’t reconcile myself to the church’s teachings on women, like women not being allowed to be church leaders and polygamy in the afterlife . I tried to be a Mormon feminist but that was exhausting.

What do you do just for the hell of it?

I have very non-eccentric hobbies. I like to read, to have dinner with friends and junk out on TV like everybody else. I love to walk my dog, who is a little white monstrosity. In Idaho they’d call him a fake dog.

What next? Back to academia?

I think I might try some more writing. It was so hard learning how to do it properly it seems a waste of all that effort not to do more of it.

• Educated by Tara Westover is published by Hutchinson (£14.99). To order a copy for £12.74 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min. p&p of £1.99