For example, lots of childhood stress, by way of glucocorticoids, impairs construction of the frontal cortex, producing an adult less adept at helpful things like impulse control. Lots of exposure to testosterone early in life makes for the construction of a highly reactive amygdala, producing an adult more likely to respond aggressively to provocation. The nuts and bolts of how this happens revolves around the massively trendy field of “epigenetics,” revealing how early life experience causes long-lasting changes in gene expression in particular brain regions.
