The study did genome sequencing for both those exposed and their children, which allowed the researchers to detect how many new mutations had been inherited from those exposed. A number of new mutations appear with each generation, so the team was looking at a higher rate than found in controls born after the event.
And the researchers found nothing. Their search was sensitive enough that they were able to detect the effect of parental age on the number of new mutations (old parents pass on more mutations to their offspring), but it saw no effect from the dose of radiation their parents had received. Parental smoking and drinking had no impact on their offspring’s DNA as well.
One of the radioactive elements spread widely by Chernobyl was a radioactive isotope of iodine, which causes elevated thyroid cancers. As expected, a number of people exposed to the Chernobyl debris have since developed this cancer, and the researchers obtained both cancerous and healthy tissue from them. Again, they sequenced the genomes and looked at the mutations that occurred in these cancers.