Since everything is made up (see post linked in first comment) you get to control what you think and how you react to things.
Yes, brain chemistry is a factor. Do what you have to do on that front because that can indeed be a strong one. Apart from that, and perhaps acute trauma, you get to decide what bothers you, what excites you, what upsets you, what drives you.
Were you taught that something was supposed to bother you? Is the only reason it DOES bother you is because you were told that? Those are things that can change, that YOU can change.