A grainy new teaser for the Wolverine solo film Logan flickers grim scenes from the lab where X-23, also known as Laura Kinney, has just undergone radiation poisoning. In the comics, Wolverine’s clone-daughter is exposed to huge amounts of radiation to activate the mutant genes she shares with her clone-dad — the same ones that allow him to heal at will. Both inside and out of the Marvel Universe, radiation can definitely activate genes — but offscreen, it’s something DNA wants to avoid at all costs.

After her genes are activated by radiation, X-23’s adamantium claws are surgically inserted into her hands, without any anaesthetic. The scientists working on her — presumably led by bad guy Dr. Zander Rice — assume that the radiation has worked on her genes rapidly enough that her mutant powers are already activated and she will be able to heal herself. This is a cruel and risky assumption: When real-life humans are exposed to radiation, some effects are immediate, but others take years to develop. If radiation is strong enough — as it was with people exposed to atomic bomb radiation — cells can die within hours or days, through the inability to either function or reproduce. But if damage occurs on the DNA level, the long-term effects can take years to manifest.

Radiation comes in many types — X-rays and alpha and beta particles are most common — but they all are tiny enough to penetrate cell walls and nuclear envelopes to wreak havoc on DNA, the molecule that encodes all of our genetic information. If you imagine a stretch of DNA as a ladder, the rails make up its backbone, and the base pairs make up its rungs; in the process known direct action, the radiation physically breaks the ladder and the rungs, thereby messing up the structure of our genes. Indirect action occurs when the radiation knocks electrons out of the molecules that make up DNA, forming charged molecules known as free molecules. These rogues, like radiation itself, can also knock into genes and change their structure.

Presumably, this is what X-23’s doctors are aiming for: They must know that her mutant genes cannot be activated unless their structure is somehow changed. In this way, some cells don’t become cancerous until certain genes, like the notorious “tumor suppressor gene” p53, become mutated and can no longer serve their function — or serve a different one. This is not always a bad thing, but it is unpredictable: In 2013, when scientists at Harvard Medical School mutated a mouse gene called Lin28a so that it was active all the time, it unexpectedly conferred Wolverine-like abilities to mice, allowing them to regrow parts of limbs that had been damaged.

Still, Rice and colleagues seem to miss a crucial part of DNA damage by way of radiation: The process is largely believed to be stochastic — that is, totally random. By exposing X-23 to seemingly huge and dangerous amounts of radiation, they have a higher chance of activating her mutant gene, but they also run a greater risk of causing other unwanted abnormalities in her cells as well. Lucky for X-23, she’s got more than genetic tools to wreak revenge.