I don't think he is discounting the heritary factor in mental health rather instead concentrating on what can be addressed.

The beginning of the book - which is about Cognative Behaviour Therapy (CBT) - talks about negative automatic thoughts. As he points out these thoughts stem from the core beliefs about ourselves - those ways of thinking that were reinforced by lifetime experience. These automatic thoughts affect our life choices, behaviour, and decisions. They are at the heart of our Anxieties and to an extent what triggers Depression too.

The rest of the book is about strategies to deal with and change the negative into positive.

It takes a great deal of hard work - one actually ought to complete all the charts and forms provided in the book.

I have read the book in conjunction with CBT with one of my psychiatrists and I am not the same person I was even two months ago.

Admittedly it is not for everyone. I stress again that one actually has to do the homework - and continue to do so even after completing the book/program.