The Times Australia
The Times World News

.
The Times Real Estate

.

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

The Times Features

How to Protect Your Garden Trees from Wind Damage in Australia

In Australia's expansive landscape, garden trees hold noteworthy significance. They not only enhance the aesthetic appeal of our homes but also play an integral role in the local...

Brisbane Homeowners Warned: Non-Compliant Flexible Hoses Pose High Flood Risk

As a homeowner in Brisbane, when you think of the potential for flood damage to your home, you probably think of weather events. But you should know that there may be a tickin...

Argan Oil-Infused Moroccanoil Shampoo: Nourish and Revitalize Your Hair

Are you ready to transform your hair from dull and lifeless to vibrant and full of life? Look no further than the luxurious embrace of Argan Oil-Infused Moroccanoil Shampoo! In a...

Building A Strong Foundation For Any Structure

Building a home or commercial building can be very exciting. The possibilities are endless and the future is interesting. You can always change aspects of the building to meet the ...

The Role of a Family Dentist: Why Every Household Needs One

source A family dentist isn’t like your regular dentist who may specialise in a particular age group and whom you visit only when something goes wrong. A family dentist takes proa...

Benefits of Getting an Online Medical Certificate

Everyone has experienced it. Rather than taking a break, you drag yourself to the doctor's office, where you have to wait in lengthy lines, and then you have to hurry to get that...

Times Magazine

"Eternal Nurture" by Cara Barilla: A Timeless Collection of Wisdom and Healing

Renowned Sydney-born author and educator Cara Barilla has released her latest book, Eternal Nurture, a profound collection of inspirational quotes designed to support mindfulness, emotional healing, and personal growth. With a deep commitment to ...

How AI-Driven SEO Enhancements Can Improve Headless CMS Content Visibility

Whereas SEO (search engine optimization) is critical in the digital landscape for making connections to content, much of it is still done manually keyword research, metatags, final tweaks at publication requiring a human element that takes extensiv...

Crypto Expert John Fenga Reveals How Blockchain is Revolutionising Charity

One of the most persistent challenges in the charity sector is trust. Donors often wonder whether their contributions are being used effectively or if overhead costs consume a significant portion. Traditional fundraising methods can be opaque, with...

Navigating Parenting Arrangements in Australia: A Legal Guide for Parents

Understanding Parenting Arrangements in Australia. Child custody disputes are often one of the most emotionally charged aspects of separation or divorce. Parents naturally want what is best for their children, but the legal process of determining ...

Blocky Adventures: A Minecraft Movie Celebration for Your Wrist

The Minecraft movie is almost here—and it’s time to get excited! With the film set to hit theaters on April 4, 2025, fans have a brand-new reason to celebrate. To honor the upcoming blockbuster, watchfaces.co has released a special Minecraft-inspir...

The Ultimate Guide to Apple Watch Faces & Trending Wallpapers

In today’s digital world, personalization is everything. Your smartwatch isn’t just a timepiece—it’s an extension of your style. Thanks to innovative third-party developers, customizing your Apple Watch has reached new heights with stunning designs...

LayBy Shopping