The answer can be both increase in self-esteem and increase in aggression. All of the research generally points to increase of self esteem because during puberty self awareness is very prominant which increases self esteem. I would be safe and go with self esteem. I hope this helps.
Aggressiveness is a common emotional change in teens. Teenagers are usually more aggressive than children, because during adolescence hormone production is occurring "at full force". This causes teenagers to have high levels of testosterone which causes increased aggression.
Teenagers do not usually have increased self-esteem, which is quite the opposite, as adolescence is a phase of insecurity where we are still discovering. In addition, the onset of menstruation and the onset of semen production are not emotional but physiological changes.
