Scientists find genetic ‘switch’ in mice that turns caring dads into violent brutes
Activating a single genetic switch can cause devoted fathers to attack their offspring, at least in African striped mice, new research suggests. But the gene itself was not solely responsible for this shift from attentive to aggressive paternity; Social conditions also played a role in the behavior of male mice.
The findings could reveal more about the genetic mechanisms that lead some mammal species to act as caring fathers while others abandon their young. Active paternity is rare among mammals, with only 5% of the 6,000 species of mammals that have involved dads. For this reason, scientists know much less about how paternal care works in mammals than they do about maternal care in mammals. African striped mice (Rhabdomys pumilio) are useful for studying paternal care in mammals, because males exhibit a wide range of behaviors toward pups, from huddling to keep pups warm to actively ignoring their offspring.
To determine the brain regions responsible for this behavior, the team exposed male mice to pups and then monitored their brain activity. They found that attentive fathers had greater activity in a region of the brain called the medial preoptic area (MPOA).
“Decades of work have shown that the MPOA acts as a hub for maternal care in mammals,” lead author and postdoctoral researcher Dr. Forrest Rogersresearcher at the Princeton Neuroscience Institute, told Live Science in an email.
The team then dissected the mice’s brains and measured gene activity in MPOA cells. From there, they discovered that a gene called Agouti was more active in males who attacked the young than in males who looked after them.
“Agouti is best known for his roles in skin pigmentation and metabolism, so discovering this previously unknown role in the brain for parental behavior was exciting,” Rogers said in a statement.
To confirm that Agouti expression was responsible for the transition between attentive and aggressive behavior, the team first exposed mice to pups and then injected a virus that amplified Agouti gene expression in MPOA. When the males were exposed to the young again, their behavior changed.
“We found that these males, when Agouti increased, became aggressive toward the pups,” Rogers told Live Science in an email, suggesting that this gene acted as a sort of “switch” that toggled between aggressive and caring behavior in the father mice.
Although the Agouti gene found in MPOA may have a strong link to the change in paternal care, Rogers cautioned that this molecular change is not the whole story.
“It certainly appears that for some striped mice, the increase in Agouti expression is sufficient to cause infanticide,” he said. “However, we also found that there were other factors at play, for example current social housing, which could mitigate this effect.”
When researchers moved males from group housing to solitary cages, Agouti levels fell and care increased, suggesting that the gene is influenced more by social context than food availability.
Although this study may have revealed a possible genetic change in paternity, it had important limitations. Notably, only male African striped mice were studied. And although paternal behavior varies within the species, the researchers cautioned against translating these findings to other species.
“While we do not rule out that Agouti may function similarly in other species (humans or otherwise), there is currently no evidence to suggest this specific function in humans (or other mammalian species),” Rogers said in his email to Live Science.
Rogers, FD, Kim, S., Mereby, SA, Kasper, AM, Callanan, AB, Mallarino, R. and Peña, CJ (2026). Agouti integrates environmental cues to regulate paternal behavior. Nature. https://doi.org/10.1038/s41586-026-10123-4
