On the sunniest day of the festival so far, a dramatic entrance by the pink-trousered psychoanalyst Oliver James set the tone for his controversial claim that the human genome project was a damp squib. It had so far failed to show significant heritability for certain psychological traits – proving that his own theory of nurture being stronger than nature, as posited in Not In Your Genes, was correct.

Physical or emotional maltreatment in childhood was the most important cause of adult mental illness; thus parents had the power to determine their children’s wellbeing and success in later life. The earlier the maltreatment the greater the harm: in one study of 267 children, almost all of those who had been maltreated had a mental illness by the age of 19. And maltreated people become mal-treating adults.

“It’s not that I’m a nurture flat-earther,” he declared brightly, citing biological causes of psychological traits such as autism.

On the other hand, he continued, what does explain why one sibling is different from another is by nurture, or upbringing. Parents pass things on to children in three ways: teaching, modelling and identification. Look at Peaches and Tiger Lily Geldof, or young David Bowie and his half-brother Terry. Terry was emotionally maltreated, while David was encouraged. Terry became mentally ill, while David went on to enjoy huge success.

To say certain traits are “in the genes” was therefore wrong. We can choose to change. “It’s difficult, but possible,” he said. “By meeting the needs of children we can rebalance our repulsively inequal society.”

We do have the power to change ourselves, concurred the comedian and writer Ruby Wax, who has an OBE for services to mental health. “And it starts with destressing about stress.” Frazzledom is the state we’re all living in and, unlike our early hunter-gatherer forebears, we’ve lost the fight-or-flight braking mechanism that could protect us from 24/7 stimulation and consequent anxiety. To a packed and empathetic audience, she explained that she’s been on medication for depression for over 20 years, but has discovered the power of mindfulness – a kind of meditation – to “cool the mind” sufficiently to let her know when another episode is coming.

“It’s like a muscle you can develop. The more you practise the stronger it gets and the more able you are to train your thoughts away from those nagging inner voices,” she said, revealing that she was ill during the writing of her book A Mindfulness Guide for the Frazzled but that, thanks to mindfulness, it passed in days rather than months and she was able to finish it – a feat she called a “miracle”.

In typical upbeat manner she compared Frazzledom to the plot of Breaking Bad, the cult US drama, but rather than meth that is cooking up, it’s the stress hormone cortisol.

“Mindfulness encourages neoplasticity, so has the ability to change the neuron patterns in the brain. Regular practice can change your life,” she said. Its potential for the teachers and carers of children did not go unremarked.

It was a tearful Richard Holloway who attempted to answer the vexed question of why God allows so much human suffering. The author of The Little Book of Religion’s voice caught as he cited the example of the little boy hanging on a rope in Auschwitz, and someone asking where is God now? The answer he got was that God was that little boy.

We humans are capable of horrific acts but the best answer to suffering, he concluded, was to help those enduring it. And the best way to try to explain things is silence. “I’d rather live with questions than answers,” he said.

And so we were spared the thunderbolt at the end of a scorching day.