Why do identical twins end up having such different lives?

This is a follow-up to the posts on Angelina Jolie, especially The ‘Fortune’ of Angelina Jolie.

There I argued against the biological determinism of much work on DNA and drew attention to the influence of how and where we live (the ‘environment’). DNA is a metabolic molecule. It reacts to its circumstances.

This is illustrated by this study of identical twins, most of whom developed very different medical conditions. How so if they had identical genetic make-ups? The answer is epigenetics. This from the study linked to below:

“Essentially, epigenetics is the mechanism by which environmental changes alter the behaviour of our genes,” he says. “This involves a process known as methylation, which occurs when a chemical known as methyl, which floats around the inside of our cells, attaches itself to our DNA. When it does so, it can inhibit or turn down the activity of a gene and block it from making a particular version of a protein in our bodies.” Crucially, all sorts of life events can affect DNA methylation levels in our bodies: diet, illnesses, ageing, chemicals in the environment, smoking, drugs and medicines.

From the ‘epigenetics’ link above:

Food, pollution, toxic chemicals (such as those found in hard clear plastics), drugs, stress, even exercise and social interaction can all affect the epigenome and alter its attitude towards DNA. (my emphasis)


via Why do identical twins end up having such different lives? | Science | The Observer.

For more see the book Identically Different: Why You Can Change Your Genes by Tim Spector. 

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