Podcast Review: A Thorough Examination with Drs Chris and Xand – The twin effect

Are we truly able to change? How can we make this happen? How much control do we have over what happens to us? These are questions I often find myself mulling over in the New Year when facing the annual bombardment of self-help advertising, and I am sure I am not alone in that. When faced with the idea that we must leave behind our old selves, it is easy to wonder whether that is even possible.

In the new season of their podcast 'A Thorough Examination', Drs Chris and Xand van Tulleken tackle this problem. The nature versus nurture debate has long been a matter of contention in science, and it is through this lens that the brothers explore whether people can change who they are. As identical twins, they describe themselves as having been 'born as essentially the same person' and so they know what it is like to struggle with individual identity better than most, and how we can sometimes feel that our destiny is handed to us at birth. Over eight episodes they seek the opinion of friends, family, and various scientists on how our genetics and environment come together to make up who we are, and how we can achieve true and positive change.

Having successfully ignored most of my current New Year's resolutions, I began listening with the slight hope that I would be told it's not really my fault and that we are shaped by forces out of our control. Episode one, 'The twin effect', makes it clear that it is never as black and white as that. The complexity of this debate lies in uncovering what traits are governed by what, and once we know this, what do we have to do to change? Chris' motivation for understanding this is admittedly far more selfless than mine. He wishes to be a better doctor and a better father, and ultimately, he wants to improve his relationship with his twin. Xand is less convinced that change is possible, and Chris aims to confront this belief and prove him wrong.

In the first episode we hear from geneticist Dr Clare Llewellyn, Chris and Xand's mum, and from another pair of identical twins named Mia and Alexandra. The episode serves as a thoughtful ode to the complexity of growing up as a twin, and how this experience can be used by scientists to help us better understand human development. Chris and Xand explain that as twins, it can be hard to feel like different people and in that sense your genes can feel like your destiny.

Dr Llewellyn, who runs the Gemini twin study, provides us with the scientific perspective. She explains that twin studies are a golden opportunity for scientists to understand how genetics and environments shape us, as identical twins are genetically identical and so any observed differences must be caused by environmental factors. Chris asks her whether she believes people can change, and she says that nothing about us is set in stone and supports this conclusion with a recent example of how she managed to condition herself out of a life-long aversion to fruits and vegetables.

Chris and Xand's mum reflects on their dynamic as children, and how she believes that twins polarise one another in an attempt to defy their genetic similarities. Her first-hand experience is therefore that willpower and environmental factors can overcome genetics.

Mia and Alexandra offer a different perspective on twinhood, as they were adopted by different families and although they kept in touch, they did not grow up together. Their insight into the influence of non-shared environments was particularly interesting to me as it highlights how we do have the potential for change. Their environmental differences have given them entirely separate identities despite their identical genetic makeup; they have different career and life goals and are even three inches apart in height. This reminded me of the pessimism expressed by Xand at the beginning of the episode and suggests that his experience as a twin in a shared environment has led him to believe we are not capable of change, but this is not the case. I found this particular narrative incredibly moving, we have all struggled with our identities before and it is comforting to hear that this is normal, and that nothing is set in stone.

The formatting of the episode was a welcome change from what I expected of a science-focused podcast. Snippets from the conversations with the guests are skillfully woven throughout, with Chris and Xand musing upon the overarching themes of identity and change in between these segments.

We get to hear everybody's perspective without repetition of the same questions, and the episode becomes deeply personal at times as the brothers reflect on the different guest conversations throughout. It all pieces together as a gentle introduction to the wider debate surrounding identity and development, which was much more pleasant to listen to as opposed to having lots of difficult concepts and new information thrown at you right from the get-go, as I often find with science podcasts. I would deem it accessible to a wide audience, regardless of scientific background.

The episode ultimately concludes that we are not defined by our genes, but we are equally not blank slates at birth. It is a strong beginning that puts the series in an excellent position to further investigate the human capacity for change, and I cannot wait to hear where they go next.

All episodes of 'A Thorough Examination with Drs Chris and Xand' are available to listen to on the BBC Sounds website, Spotify, and most other podcast platforms.