Question about radiation fallout and cancer link?

I’m American by birth, but my cousins are Jewish immigrants from the former Soviet Union. They lived in Khmelnytsky in the Ukrainian SSR, which is about 250 miles from Chernobyl, and emigrated to the United States to join the rest my family in 1993 (as an aside, not all of them came to the US—some went to Canada and others to Israel). As far as I know they did not have to evacuate as a result of the Chernobyl disaster.

According to my mom, a couple of members of her extended family from the former Soviet Union had cancer, including thyroid, brain, and prostate cancer. Most recently, my cousin who was born in 1989 was diagnosed and treated for thyroid cancer a couple of years ago here in the US.

I was just wondering, based on the opinions of any Chernobyl experts, doctors, and scientists out there, whether the radiation fallout likely/possibly had any effect on the incidences of cancer in my family? Especially my cousin who was born after the disaster.

This is purely out of budding curiosity as a result of watching Chernobyl on HBO. When I was watching I couldn’t help but think of my family who lived there at the time.