Realism?

Realism is a controversy in itself; if an author creates a character, where do that character's traits come from? The author has to put something of him/herself into the character, using personal knowledge and feelings to create the persona. Is there a perfect way to write Realism?
Although Steinbeck comes across as a neutral third party telling a story, where does the dislike and mistrust of "the big man" or the police come from? He either infuses his own opinion, or feeds in the opinion of others (that he created in his mind) from that era. Hoovervilles were a fact then, but the character interaction with the fact has to be created,
I am most definitely not knocking Steinbeck (or any other author) in abilities to create a novel. I believe it's what makes an author appealing to the reader, and in the decision if I'll continue reading that author's works.