The town of Chernobyl in Ukraine is often associated with the nuclear disaster. In April 1986, a catastrophic explosion occurred at the Chernobyl Nuclear Power Plant, leading to widespread radioactive contamination. The surrounding area was evacuated, and the effects of radiation exposure were felt for decades. Interestingly, some residents returned to the area despite the risks, and studies have shown that a portion of these returnees exhibited unexpected health resilience. One notable case is that of a family who returned and remained healthy, despite living in a contaminated zone. This family's experience is not isolated; many returnees seem to have developed a form of resistance to radiation effects. Researchers have identified a genetic mutation in some of these individuals that may contribute to their resilience.

Which of the following, if true, most undermines the implications made within the passage?