A new documentary on Netflix called “You Are What You Eat” features sets of identical twins who adopt different diets for eight weeks. One twin follows a vegan diet while the other follows an omnivorous diet. The experiment is interesting because the twins are genetically identical and have similar health before the trial.
The documentary highlights the importance of twin studies in advancing our understanding of various topics. Twins are often used for comparisons because they share almost all of their genes and grow up in the same environment. This makes them ideal for randomised controlled trials, where participants are randomly selected for an intervention and others serve as controls. Randomised trials are considered the gold standard in evaluating effectiveness.
Although identical twins are not always necessary for such trials, they can help ensure that the treatment and control groups are as similar as possible. This is especially important when there are a limited number of participants, as was the case in the Netflix study with only 44 participants.
Twins are also valuable in research when randomised trials are not feasible due to ethical or practical reasons. By comparing differences within sets of identical twins, researchers can eliminate genetic and common family factors and have more confidence in causality. While using twins does not completely solve the issue of omitted factors, it does help reduce it.
The fascination with twins and their contribution to research dates back to Sir Francis Galton in 1875. Galton observed the striking similarities between twins and argued that this proved the importance of nature in shaping our dispositions and health. Researchers have since developed methods to disentangle genes and environment, with the main approach being comparing identical twins to fraternal twins. If identical twins are more similar than fraternal twins, it indicates that genes play a significant role.
However, twin studies have limitations. Twins are a select group and findings may not always apply to the broader population. Assumptions about the common family environment can also affect the results of twin heritability studies. Additionally, there has been misuse of twin research findings, such as promoting eugenics based on the belief in the power of nature.
Nevertheless, twin studies have been conducted for decades and continue to play a crucial role in advancing our understanding of various topics. With advancements in technology and data linking, the future of twin research looks promising. Twins will likely continue to contribute to our knowledge for years to come.
