Orchid Child

Kate is a neuroscientist who covets logic and order, unless she's sleeping with her married lab director, and then logic goes out the window. So does her orderly life in Manhattan when she's fired over the affair and Kate's mother presses her to accept responsibility for her fifteen-year-old nephew, Teague, an orchid child who hears voices and talks to trees but rarely people.
To salvage her career, Kate agrees to conduct a study in West Ireland where hostile townsfolk rebuff her study of their historically high rate of schizophrenia and a local chief Druid identifies Teague's odd perceptions as the gift of second sight, thrusting a bewildered Kate on a trail of madness, magic, and armed rebellion that leads to her own grandparents, who were banished as traitors from the same town.
When a confrontation with the chief Druid endangers Teague's life, Kate lands at the intersection of ancient Celtic mysticism and 21st century neurodiversity, where the act of witnessing old wounds can heal suffering in both past and present - even hers, if she can accept the limits of science and the power of ancestral ties.