There are all kinds of sibling relationships. Some people are tight knit with each of their siblings in a different way, while ohers are distant for various reasons, such as large age gaps. Then there are the multiples, like twins and triplets, have the best advantage.
There isn't a single moment in the lives of twins when they have existed independently of each other. There is something unique and special about being a twin. For example, you get to share the rare moments that most siblings don't. My brother and I sat next to each other at our high school graduation and having shared every moment of school up until that point, it was an amazing feeling hearing his name called right after mine to walk the stage. Most siblings have to watch from the stands, but I got to quietly chat with my brother during the ceremony. Something else that makes twins unique is that you get to take each milestone together. Since we're the same age, we got to grow up together, experience the awkward stages of middle school together, and learn how to drive at the same time.
I think the one of the best parts of being a twin is that you never have to be referred to as "someone's little sister." When we had the same teachers, they got to know us independently without thinking of us as the others' younger or older sibling.
You get to really be your own person because you want to establish yourself as an individual. Twins can often be seen as one person (especially in identical twins) when that couldn't be further from the truth. Our personalities were really developed because we wanted to make sure we were our own person. Fraternal twins have an advantage here, because they have an easier time establishing differences because they do not look the totally alike.
I definitely think the best part of being a twin is that you always have someone there. All throughout school, I always had someone that was there with me. I was so glad I didn't have to go to middle school or high school alone. I didn't have to go through changes alone, even if our changes were very different from each other. As we got older, we became friends because eventually, all we will have is each other. We grew up together and when we went our separate ways for college, it was hard to leave someone we have spend our whole lives with. Being away from each other for the first time can be really sad. I have grown to miss my brother when I go to school and find myself wanting to talk to him more than I ever did when I lived at home.
I have always enjoyed being a twin and I am so thankful that I was able to experience having a sibling in such a unique way.