The Times Australia
The Times World News

.
Men's Weekly

.

Netflix's You Are What You Eat uses a twin study. Here's why studying twins is so important for science

  • Written by Nathan Kettlewell, Senior lecturer, Economics Department, University of Technology Sydney
Netflix's You Are What You Eat uses a twin study. Here's why studying twins is so important for science

A new Netflix documentary, You Are What You Eat, showcases sets of identical twins as they adopt different diets. For eight weeks one twin follows a vegan diet while the other one follows an omnivorous diet. The experiment is compelling because, being genetically identical, the health of each twin is very similar before the trial.

I won’t spoil the ending for those who haven’t seen it, but if you prefer the drab writings of academics over the glitz and glamour of Netflix, you can read the published paper in the journal JAMA Network Open[1].

The documentary underscores the extraordinary contribution twin studies make to advancing our understanding of the world. But this goes well beyond comparing different diets.

British polymath Sir Francis Galton first documented[2] the striking similarities of twins in 1875, arguing this proved “nature” was an important contributor to our dispositions and health. Since then, twins have been used extensively in research. What is it then that makes twins so special, and how do researchers harness the power of twins?

Twins as comparisons for each other

The Netflix documentary highlights one important feature of twins – they are good for making comparisons. Identical twins share nearly all of their genes, and usually grow up in the same household, meaning they experience the same parenting, schooling and so on.

The documentary is an example of a randomised controlled trial[3], where participants are selected at random for some intervention (like a new drug) and those not selected serve as controls (in drug trials they might get a placebo). Randomised trials are normally seen as the gold standard in evaluating what works.

Read more: Randomised control trials: what makes them the gold standard in medical research?[4]

We don’t actually need identical twins for such trials. In fact, relatively few[5] trials use twins. But twins can help to ensure the treatment and control groups are as similar as possible. This is especially important when there are few participants. In the Netflix study, there were only 44. Without twins, their results would have been more uncertain.

For ethical reasons or just sheer practicality, we can’t always run randomised trials. This is where twins can help us out. Say we want to know the effect of education on earnings[6], or the effect of smoking on developing lung cancer[7].

These questions, and many more, have been tackled by comparing the differences within sets of identical twins (for example, where one twin smokes and the other doesn’t).

By focusing on differences between twins, we eliminate genetic and common family factors, and can be more confident about causality. Using twins doesn’t fully solve the problem of omitted factors, but it helps to reduce it.

Two women with blonde dreadlocks in a commercial kitchen with various food trays in front of them
Still image from You Are What You Eat. Netflix

Twins and heritability

Galton’s fascination with twins stemmed from wanting to know why we are the way we are. Is it our genes (nature), or is it our upbringing and personal experiences (nurture)? His early observations were informal, but eventually researchers developed sophisticated methods to disentangle genes and environment.

The main approach is essentially to see whether identical twins, who are genetically the same, are more similar than fraternal twins, who on average share only 50% of the gene variants that make us unique. If the identical twins are more similar, that indicates genes matter.

For example, twin studies have shown that around 40% of individual differences in personality[8] can be explained by genes, along with as much as 80–90% of differences in height and weight[9] at the end of childhood.

Read more: Curious Kids: Why do people grow to certain sizes?[10]

Limitations and misuse of twin research

One drawback to twin studies is that twins are a select group, and findings may not always generalise to the broader population. Only about 1.4% of births in Australia are twins[11].

Twin heritability studies also rely on strong assumptions[12], like that the common family environment matters to the same extent for identical and fraternal twins. This can be overcome by focusing on identical twins reared apart[13], but these studies are rare.

There has also been some misunderstanding and misuse of findings from twin studies. Galton’s belief in the power of nature led him to promote eugenics[14], the idea of selective breeding to achieve “genetic superiority”, which had devastating consequences[15] in the 20th century.

But our genes are not our destiny. While a certain combination of genes may raise the likelihood you’re extraverted, who we grow up to be is a complicated interplay between genes, upbringing and personal experiences. Even disorders with a genetic basis, like Alzheimer’s, are rarely certain to occur, and we can take actions to reduce our risk.

A person carrying two baby carriers with identical twin babies Identical twins are actually quite rare. Shutterstock[16]

The future of twin research

Twin studies have been conducted for decades, with more than 60 twin registries[17] operating around the world. In Australia, the largest registry is Twins Research Australia[18], who have around 75,000 members.

With more opportunities to link data, genome mapping, and advances in machine learning, what we can learn from twins will only increase in the future. And we can expect twins to continue to play a key role in advancing our understanding of the world for many years to come.

References

  1. ^ in the journal JAMA Network Open (jamanetwork.com)
  2. ^ first documented (academic.oup.com)
  3. ^ randomised controlled trial (www.ncbi.nlm.nih.gov)
  4. ^ Randomised control trials: what makes them the gold standard in medical research? (theconversation.com)
  5. ^ relatively few (www.sciencedirect.com)
  6. ^ education on earnings (www.jstor.org)
  7. ^ smoking on developing lung cancer (pubmed.ncbi.nlm.nih.gov)
  8. ^ 40% of individual differences in personality (psycnet.apa.org)
  9. ^ 80–90% of differences in height and weight (www.ncbi.nlm.nih.gov)
  10. ^ Curious Kids: Why do people grow to certain sizes? (theconversation.com)
  11. ^ 1.4% of births in Australia are twins (www.aihw.gov.au)
  12. ^ strong assumptions (www.apa.org)
  13. ^ identical twins reared apart (www.science.org)
  14. ^ eugenics (en.wikipedia.org)
  15. ^ devastating consequences (encyclopedia.ushmm.org)
  16. ^ Shutterstock (www.shutterstock.com)
  17. ^ more than 60 twin registries (www.sciencedirect.com)
  18. ^ Twins Research Australia (twins.org.au)

Read more https://theconversation.com/netflixs-you-are-what-you-eat-uses-a-twin-study-heres-why-studying-twins-is-so-important-for-science-221012

Times Magazine

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Science Behind Reverse Osmosis and Why It Matters

What is reverse osmosis? Reverse osmosis (RO) is a water purification process that removes contaminants by forcing water through a semi-permeable membrane. This membrane allows only water molecules to pass through while blocking impurities such as...

Foodbank Queensland celebrates local hero for National Volunteer Week

Stephen Carey is a bit bananas.   He splits his time between his insurance broker business, caring for his young family, and volunteering for Foodbank Queensland one day a week. He’s even run the Bridge to Brisbane in a banana suit to raise mon...

Senior of the Year Nominations Open

The Allan Labor Government is encouraging all Victorians to recognise the valuable contributions of older members of our community by nominating them for the 2025 Victorian Senior of the Year Awards.  Minister for Ageing Ingrid Stitt today annou...

CNC Machining Meets Stage Design - Black Swan State Theatre Company & Tommotek

When artistry meets precision engineering, incredible things happen. That’s exactly what unfolded when Tommotek worked alongside the Black Swan State Theatre Company on several of their innovative stage productions. With tight deadlines and intrica...

Uniden Baby Video Monitor Review

Uniden has released another award-winning product as part of their ‘Baby Watch’ series. The BW4501 Baby Monitor is an easy to use camera for keeping eyes and ears on your little one. The camera is easy to set up and can be mounted to the wall or a...

The Times Features

Running Across Australia: What Really Holds the Body Together?

How William Goodge’s 3,800km run reveals the connection between movement, mindset, and mental resilience As a business owner, I’ve come to realise that the biggest wins rarely com...

Telehealth is Transforming Healthcare Services in Australia

It has traditionally not been easy to access timely healthcare in Australia, particularly for people who live in remote areas. Many of them spend hours on the road just to see a...

Launchd Acquires Huume, Strengthening Creative Firepower Across Talent-Led Marketing

Launchd, a leader in talent, technology and brand partnerships, has announced its acquisition of influencer talent management agency Huume from IZEA. The move comes as the medi...

Vietnam's "Gold Coast" Emerges as Extraordinary Investment Frontier and Australian Inspired Way of Life

$2 Billion super-city in Vung Tau set to replicate Australia's Gold Coast success story A culturally metamorphic development aptly named "Gold Coast" is set to reshape Vietna...

Choosing the Wrong Agent Is the #1 Regret Among Aussie Property Sellers

Selling your home is often one of the largest financial transactions you’ll make, and for many Australians, it’s also one of the most emotional. A new survey of Australian home se...

Travel Insurance for Families: What Does it Cover and Why it’s Essential

Planning a family trip is exciting, but unexpected mishaps can turn your dream vacation into a stressful ordeal. That’s where travel insurance comes in—it’s your safety net when ...