Senior Gretchen Moore’s relationship with her identical twin, senior Anna Moore, has not changed much since they were younger, when they pretended to be each other in seventh grade science class.

“We were super close and we would do everything together. We would literally spend hours playing Barbies together in our basement. I think the only thing that has changed is we have come to learn to be a little more independent,” Gretchen said.

She said having a twin comes with many benefits and very few drawbacks. Having a twin, Gretchen said, changes your sense of individuality to a degree.

Gretchen said, “The only thing I dislike about having a twin is sometimes it’s hard to be known as your own person. Everyone usually associates me with having a twin unlike my friends and family that really know me as my own person.”

Junior Sage Mehta said she is also mistaken for her identical twin, junior Jade Mehta, by people who do not know them. She said she agreed with Gretchen and said it can be hard to be one unique individual in a set of twins.

“The worst part about being a twin is definitely just the concept that you’re not the only ‘you’ in a sense to a lot of other people, so it’s hard to be an individual,” she said.

Identical twins, or ‘monozygotic twins,’ share all of their genes. This is a result of a single fertilized egg that splits in two, allowing two genetically identical children to develop during pregnancy, according to Psychology Today. Identical twins share DNA and look the same, while fraternal twins are a result of the fertilization of two separate eggs during the same pregnancy, and these twins do not often look as similar.

According to author Nancy Segal, who has a doctorate in twin psychology and behavior, the most surprising discovery of identical twins over the course of her career is how identical they can be in terms of their behavior, even after spending many years apart in some cases.

In regard to twin similarity and human behavior, she said via email, “The twin study is a simple and elegant way of discovering the contribution of genes and environments to individual differences in behavior and physical traits. This is done by comparing how similar identical twins and fraternal twins are. Greater identical twin similarity is consistent with genetic effects.”

However, Jade said she is convinced there is more to a person than DNA and environmental influence.

Jade said, “I’m pretty convinced the whole ‘you are who you are because of DNA and the environment’ isn’t the whole story because I’m kinda the proof of that.”

Jade said she and Sage have different interests both inside and outside of school.

“We are the same in many ways but with different applications. So like I play the piano and can spend hours playing with no problem, while Sage can spend hours drawing and I’d be so bored doing that,” Jade said.

Gretchen said her and Anna, who share some of the same friends and play the same sports, also share similar beliefs. However, like Jade and Sage, she said her and her sister also have different interests.

“Some things that make Anna and I similar are definitely our beliefs. Our whole family is Catholic so we have very similar morals in the ways we think people should be treated, which is with love and respect. We also have the same friends so we tend to be around people who are very kind and funny. One thing that is different is I tend to stress out about more things, and Anna is more laid back. I also love to run and Anna hates it.”

Jade said her and Sage also share the same friends. She also said she thinks of herself as the more laid-back twin.

Sage said having a twin means having someone to relate to and share experiences with.

“The best part is just always having someone (else) there that knows you really well, so whenever you reference things someone can also relate too,” she said.

Gretchen said having an identical twin is amazing.

“My favorite part about being a twin is always having someone there for you, whether it be when I was little and always having someone to play Barbies with or now just having someone to eat lunch with. People have heard this a billion times but being a twin is truly having a built-in best friend—it’s amazing,” she said.