It is tough to say, as the brain is quite a complex machinery. In regards to social anxiety, it is similar to the cause and effect question of the chicken and the egg.
Is the amygdala responding to the hormones? Is the amygdala trying hard to make sense of the ramped up signalling as a result of the hormones' introductions?
There is also the venturing out on one's own without parental supervision angle. Prior to that, one's naivete in recognising deception or malevolence is safeguarded by the parents. On one's own, uncertainty could increase the amygdala's activity. And without resolution of such uncertainties, a vicious circle is created.http://www.sciencedaily.com/releases/20 ... 100041.htm
The above article suggests a certain perspective: the ability to assimilate the unfamiliar quickly enough and move on to other unfamiliars. And that leads to questions of genetics or environment that help or hinder such ability.