Cancer is a really big deal, but I never thought about it like that because no one in my family had ever had it before. Then my twin sister, Aaliyah, was diagnosed with Ewing’s sarcoma in November 2016. We were only 9 at the time. I was pretty scared.

I didn’t talk to my mom or dad about it very much, because I didn’t want to put more stress on them. They had a lot going on, and it felt like talking about how scared I was would...