Theories of Rebellion, Conflict, and Separation. Temperament, childhood experiences, opportunities, coping skills, and social life all determine whether adolescence is calm, moderately problematic, or tumultuous. Quarrels between adolescents and their parents tend to signify a change to a more reciprocal adult relationship.
Adolescence begins with puberty.
During puberty, the sex organs mature and the individual becomes capable of reproduction. The pituitary gland mediates hormonal changes. In boys, the onset of nocturnal emissions and the growth of the testes, scrotum, and penis signify sexual maturity. Children come to understand the principles of conservation. This marks the beginning of abstract reasoning.