You'll want to leave it out. if it isn't conducive to the content of your paper, it's more like a distraction from what you're trying to say. parentheses might be a "safe" way to signify a side topic, but it weakens the paper as a general statement because the reader has to pause and take a moment to absorb a new topic before going back to what you were saying
Answer:
He means that your own conscience must tell you what is right or wrong, and it does not matter how many others agree or disagree with you. As Atticus explains to Scout, this is why he is defending Tom Robinson, even though most of the town thinks he is wrong for doing it