In experiments on lab mice, scientists found that the presence of a molecule called interleukin-17a (IL-17a) — known for its role in autoimmune diseases and fighting infections — also impacts brain development before birth. When IL-17a activity was artificially blocked in pregnant mice, their offspring showed neurotypical behavior. But when left unchecked in mice with a specific inflammatory gut microbiota, their pups developed autism-like symptoms.

Even more shocking: when healthy mice received fecal transplants from the inflammatory group, their pups also developed these neurological changes — proving it was the mother’s gut bacteria making the difference.

Lead researcher John Lukens explained, “The microbiome is really important to the calibration of how the offspring’s immune system is going to respond to an infection or injury or stress.”

This discovery marks a potentially game-changing moment in autism research. While the results