Science supports the idea that the frontal lobe is not fully developed until the late 20s. One of the biggest concerns among young people is their impulsivity and poor judgment, both of which are controlled by the prefrontal cortex. I find it alarming to hold a minor fully responsible for their actions when, unlike adults; part of their brain is not fully developed. Biologically, they are not yet mature and their executive system is not fully functioning. In addition to profound physical changes in the brain, Deborah Yurgelun-Todd of Harvard University says adolescents also experience dramatic hormonal and emotional changes. For example, testosterone, one of the hormones with the most dramatic effect on the body, is closely associated with aggression and increases tenfold in adolescents (2004). Juveniles suffer from significant neurological deficits which can increase delinquency; therefore, holding them to the same standards as adults is