Rise of the super siblings: How important are genes in sporting success?

To reach the exalted heights of Olympic-level sport, it takes supreme dedication, training and talent to beat the fiercest competition – so how is it that despite these obstacles, two champions from the same family can come along at once, repeatedly?

At the Tokyo Olympics this summer, no fewer than 10 sets of siblings, including three pairs of twins, have been selected to represent Team GB alone.

Each sibling will compete in the same sport as their brother or sister, with the relevant disciplines including cycling, swimming, boxing, rowing, tennis, hockey, gymnastics and athletics.

The 10 pairs are a rise from the six pairs that represented Team GB at the 2016 Olympics in Rio de Janeiro.

They are:

Emily and Tom Ford – rowing

Charlotte and Mathilda Hodgkins-Byrne – rowing

Joe and Max Litchfield – swimming

Adam and Simon Yates – cycling

Luke and Pat McCormack – boxing

Jamie and Andy Murray – tennis

Hannah and Jodie Williams – athletics

Tiffany Porter and Cindy Sember – athletics

Jessica and Jennifer Gadirova – gymnastics

Harry and Hannah Martin – hockey

But what’s going on with the families producing these sports machines?

Are the inherited genetic traits shared by these siblings the key to their success, or is it more about how they were brought up? Is it down to sharing training regimes, or their psychology? Can scientists even unpick this thorny nature-versus-nurture conundrum?

The Independent spoke to leading researchers in sport and genetics from Edinburgh University and Loughborough University to try and find out how much the future of sport is about examining genetic traits, and how much remains in the innumerable other factors at play.

Professor Dave Collins from the University of Edinburgh, an expert in sport science ​​who has worked with 80 World or Olympic medallists, tells The Independent he was “not particularly surprised” about the number of sibling pairs going to the Tokyo Games.

“Humans are biopsychosocial – a long word, a good Scrabble score, but important for what we’re talking about here.

“Things happen because of biological things – so twins become successful at sport because of biological reasons in that they’re the right size and shape, etcetera. Psychologically they have developed the right skills because they’ve had the right psychological skills developed in them by their parents or whoever brought them up, and socially, they’ve been in an environment that’s worked for them – that environment has helped them.

“So against that background it’s not particularly surprising that people from the same family – twins or otherwise – actually qualify. Biologically, psychologically and socially they’ve got a lot going for them that’s the same.”

However, the amount which these three factors come into play can be very different, Professor Collins says. “To an extent, the biological aspects determine more about what you can’t do than what you can do [at the top tier of sport].

“If you match, by serendipity, a match between parent and child, and mum and dad are encouraging you to do a sport at which you have the right biopsychosocial skills to be successful – QED (as has been shown),” he says.

The latest science examining genetics’ role in sporting success backs up Professor Collins’ summary.

“At the moment we’re at a point of understanding with genes and genomics where we know that they’re important, and we know they have an action, but we can’t completely deconvolute what is happening,” says Dr Liz Akam, a lecturer in biochemistry at Loughborough and specialist in the role of genetics in athletes.

“We can find certain associations – there are a handful of key genes which are associated with sporting performance, like aerobic fitness or strength. But that’s quite binary (in that those genes are either present or not) – and it leaves a gap between our understanding of it and the full [implications for athletes].

“Sports are still very obsessed with genes, they continue to believe they are a key piece of the puzzle, but we also need to understand elements, which we still haven’t fully grasped, of the ‘epigenetic’ modifications.”

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These “epigenetic” changes are real chemical alterations in a person’s DNA but are fascinating because such changes are reversible and do not change a person’s DNA sequence. However, their effect is that they can change how your body reads a DNA sequence and as a result, how it reacts to environmental factors, thereby affecting sporting performance.

“We’ve only realised in the last 10-15 years that the DNA contained in a cell’s nucleus can be modified by behaviour, lifestyle, parenting even,” says Dr Akam. “All of these lay down subtle modifications, and I think it’s in that area that we still lack complete understanding.”

“With the pairs of siblings, they are going to have inherited some particularly clear traits. For example, a lot of sports teams are beginning to do some genetic profiling with their elite athletes. Whether they’re finding any real utility with it remains to be seen.

“The siblings in team GB will benefit from a shared inheritance, at the level of DNA. They may also benefit from a shared environment, in terms of epigenetics.”

Dr Akam suggested genetic profiling could also reveal other shared traits among siblings, for example, endurance capacity, and together with modern knowledge of the newly recognised epigenetic processes affecting performance, the genetic picture of a modern athlete ultimately emerges as a complex mixture of innate and external factors.

“But if you were looking for rowers, you’d look for someone particularly tall and with a particularly long arm span – which usually correlates with height. Talent identification still goes along these binary paths, so the pair of sisters that are rowing – they’ve inherited some of those basic parameters. They’ve inherited a fortuitous combination of height and reach, which will give them an advantage.”