In an era when testosterone has become a cultural symbol of masculine power and restoration, science quietly offers a different story: the hormone that culture tells men to maximize is the very one that fatherhood asks them to relinquish. Clinical psychologist Darby Saxbe's two decades of research suggest that the hormonal and neurological shifts men undergo as they become fathers are not signs of diminishment but of biological readiness — an adaptation written into the body long before the first sleepless night. The question this raises is not how much testosterone a man should have, but what