Jonathan Kellerman, 73, and his son Jesse 44, are bestselling novelists and observant Jews. Jonathan is a former clinical psychologist who gave up his practice to write. Thirty eight of his books feature the psychologist protagonist Alex Delaware.

The latest Delaware thriller, Unnatural History, was published last month. Jesse, once a musician, has written five novels and a play, but has also published six books written in collaboration with his father. Jonathan’s wife, Faye, has her own flourishing series of books featuring returned-to-Judaism detective Peter Decker and his wife Rina Lazarus; and one of Jesse’s sisters, Aliza, has also begun a writing career. His other two sisters have become psychologists.

How did you start working together?
Jonathan: It was kind of serendipitous. I was working on a book outside my Delaware series called The Golem of Hollywood. I’d written about 80 or 90 pages, and then I’d put it down because I was really busy, and it was a tough book to write. Jesse and his family were visiting us [in Los Angeles] for Thanksgiving and he picked up the manuscript, and said, what is that? He read it and said I should go on with it.

I said, why don’t you do it? So we started collaborating on it, and it was a lot of fun. Then we did another one, and we have kept going. I don’t think it could have happened until Jesse was established as a novelist and an award winner in his own right. It’s not what we intended, but we’re enjoying it.

What’s the process of the collaboration? You live in different places [Jesse lives in Berkeley, California].

Jonathan: We spend about a year on each book, and there’s lots of discussion, planning, outlining. We lay the framework, the foundation. I might visit him, or he’ll come down and visit me, or we’ll get on the phone.

Once we have it set, one of us will do a draft of several pages and the other one will tinker with it. I had some experience doing this with my wife [with whom he has also collaborated]. When you’re writing a solo novel, you are proprietary and really get possessive. When you are collaborating, you have to understand it’s a different process. I don’t think we’ve exchanged one cross syllable between us.

Jesse, what’s it like writing with your father?
Jesse: I appreciate that you understand we live in different places. In previous interviews there was an assumption that, I don’t know, I was still living in my parents’ basement. No, I am a grown man with my own family [he has five children, including twins]. But, you know, my dad is always my dad.

We both recognise that the relationship between us precedes and will go beyond the collaboration between us.

We’ve been working together for about ten years. But, importantly, neither of us is coming to the page with a desire to win. We’re coming to the page with a desire to write the best book possible.

The vast majority of the time, we have the same idea about what is best for the book. On the rare occasions where we start from different places, we can both assume the other’s perspective and step outside our own ego, to say what is good for the book.

Given that he is my father, and that he’s been doing this for a long time and has had tremendous success, for him to come to this and treat me as his peer is really to his credit. I don’t think that either of us thinks of the other as father and son in the moment: we’re looking at each other as writers. He’s my partner.

Jonathan: It’s like playing in a band, which we have both done. If you’re playing with good musicians, then it’s great. I sent a manuscript of one of the Golem books to [author] Stephen King.

He said, I know your voice, I know Jesse’s voice, and you have created a new voice. It was lovely. I know this is going to sound soppy, but this is the truth: it’s like gigging with a great musician, and there’s no reason to do it if it’s not fun.

Jesse: Publishing is hard enough without fighting with the person you’re writing with. And I don’t see publishing as a competitive endeavour. I don’t feel I’m trying to outdo anybody. Maybe when you’re very young and unproven, you’re self-conscious, there is this need to succeed. But I’m well past that stage.

The joy of it for me is the sentence-by-sentence act of creation. Besides, the book market is shrinking every year — so if that’s what you’re competing at, you’re competing for small, grubby stakes.

Jonathan: We should mention that we’re both experienced fathers. I have four kids, he’s got five — I don’t know how he does it. So when you have large families, you tend to get along with people. I look at the pictures of my family and I definitely regard them as my legacy, not my books.

Can we discuss standalone novels compared with series books?
Jesse: Prior to my collaboration with my dad [the pair write together the Golem novels and the Clay Edison novels], I did write standalone novels.

That’s because the stories I wanted to write were about ordinary people caught up in difficult circumstances, people for whom the experience of a crime would be singular. In my first few books the protagonists were a secretary, a medical student, an art dealer… it was all about people caught up in the most difficult situation of their lives.

But it does mean you have to recreate the universe every time. When you do a series, certain things are given, and you don’t need to write every single character from scratch.

Jonathan: I believe the Delaware novels are the longest-running American crime series. You don’t set out to write a series. I didn’t.

What happened with me was that I wrote the first Delaware novel, When The Bough Breaks, in 1981, though it was not published until 1985. I got three bucks an hour to write it. I had a practice in psychology and was making a good living, but I said, wow, I’m finally a writer and not a schizophrenic, but I can’t afford to do this very often because there’s no money in it.
And then it became an international best-seller and I was asked to do another one.
So I did two more and at that point I thought I need to step back, and I did The Butcher’s Theatre [a standalone set in Jerusalem], which is a totally different book. Then I came back to Delaware.

Over the last 40 years I’ve done 38 Delawares and a good dozen other books. I love Delaware; Raymond Chandler was famous for hating [his fictional creation] Philip Marlowe, but Chandler was a misogynistic, racist, antisemitic alcoholic. I’m not that sort of person; I enjoy the Delaware novels because it gives me the opportunity to tell a certain kind of story.

As Jesse mentioned, you’re treading a thin line. You want your habitual readers to enjoy the comfort of the familiar, but also you want a new reader to pick up any book in the series without it being too “in-jokey”.

Jesse, have you ever been tempted to try your hand at a Delaware novel?
Jesse: [Laughing] Oh, God, no. First of all my dad is still alive! It would be like going into his closet and putting on his clothes and trying his shoes, while the man’s right there.

Moreover, the problem with being the son of not one but two prominent authors, is that you’re forever dealing with the assumption that you are junior. It’s bad enough that I’m operating in the same general genre as they are, for me to think of taking on something like that. My dad is inimitable: in 100 years’ time when he goes on to the next world, that is not what I’m lining up to do.

Jonathan: We’re hoping that genetics plays a role. My mother just died at 103 and I am 73, but I feel like a young guy, so we hope we won’t have to make those decisions.

Jesse: I couldn’t do it, we have very different styles.

Jonathan: Tom Clancy’s been dead for years and his books are still coming out. Years ago I was on a best-sellers’ list and just above me was VC Andrews. I told my kids, see, I’ve been bumped by a dead person! I don’t like it. A writer’s books are a writer’s books, finish.

How do you represent Judaism or Jewish themes in your books?
Jonathan: It’s not a big thing for me. I wrote The Butcher’s Theatre, which is set in Jerusalem, in 1988, because I lived in Israel for a time and was very entranced with Jerusalem.

But apart from that I made a calculated decision to keep my personal, religious life and my writing life separate. I wanted to be as globally appealing as possible. I didn’t want to shut people out.

Jesse: Well, the Golem books are very Jewish, the Golem deals with a mystical Jewish universe. But I’m similar to my dad in that when there is a reference to someone Jewish in my novels, it’s very matter-of-fact.

Obviously it’s a very important part of my and my father’s life, and there are stories that I might get around to telling some day. I think both of us are resistant to the idea that people can be reduced to categories.

Each of us has a multifaceted existence. I’m Jewish, but I am also a musician, a father, an American, a Californian. At the end of the day we are interested in people, rather than the categories they belong to.

Which book is your favourite of each other?
Jesse: My favourite novel of my dad’s is a non-Delaware book, Billy Straight. It’s a wonderful book. He writes from the perspective of a child, and there’s so much understanding of a child’s mind in that book, I think it’s marvellous.

Jonathan: I hate to do this! He wrote a book called The Genius, which [laughing] I thought at first was an autobiography. But I am a great fan of my son’s writing and have been since he was much younger. That’s how I knew we could work together.