Why Twin Studies are So Important to Science

Fagjun | Published 2017-09-30 16:57

Twin studies may be the key to the ultimate test of facial recognition software: being able to tell identical twins apart.



Jeffery and Thomas DelViscio are identical twins—and the FBI is very interested in them. Not as the suspects of a crime, of course, but mainly for the fact that they're twins. Twins like the DelViscios are instrumental in refining facial recognition software, because telling them apart even though they look alike is a real challenge to a machine.


Those who are parents, siblings, relatives, or friends of twins have their own ways of telling the twins apart. Each twin may have very subtle differences in their facial features that you'll only be able to discern once you've known the twins for a long time. One twin may carry themselves differently, or the other may have a distinct sense of style. We are able to recognize differences like that. Machines, howerver, may need more work to be able to tell a pair of twins apart.



What We Learn From Twin Studies


Mark and Scott Kelly [Photo by NASA]



The DelViscio twins, writing for Scientific American, tell of how they've participated in twin studies. They've had their DNA sequenced, they've had to read the same passage to a computer program, and they've undergone tests that seek to determine differences in their social media use. However, many other twins have also made contributions to scientific study.


Studying identical and fraternal twins has been a way for scientists to observe and understand “nature vs nurture”. These studies can show how much influence genes and environmental factors have on twins. If scientists can understand this, they may be able to understand the same thing in non-twins. Consider that identical twins share 100% of their DNA, while fraternal twins share only 50%. If a particular trait is more common in identical twins as compared to fraternal twins, that indicates that genes may be partly responsible for the trait.


Twin studies have also been instrumental in studying the effects of space flight on the human body. A pair of twin brothers, Mark and Scott Kelly, participated in NASA's “Year in Space” program. Mark Kelly was a retired astronaut and stayed Earth-side, while Scott was an active astronaut and set off to spend 340 days at the International Space Station.


Nature vs Nurture


Mark stayed on the ground to serve as the control variable in the experiment. This way, scientists can detect how space flight has changed Scott at the genetic level. In the early results, scientists noticed that Scott's telomeres had grown longer instead of growing shorter, which was strange. Telomeres were supposed to grow shorter as you grow older. When Scott returned to Earth, however, scientists were able to ascertain that his telomeres began growing short again.


Twin studies have also tried to whittle out the nature or nurture in human sexuality. A researcher drew data from the Swedish Twin Registry, which is the largest in the world, to determine how much nurture or nature determines a person's sexual orientation. According to the results, both nature and nurture—genes and environmental factors—play a role in the formation of a person's sexuality.


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