How do Chris's values change from the beginning to the end of the play?

Yet for all his talk about social responsibility is Chris really such a force of moral rectitude? As he admits at the end of the play, he's also a bit of a coward. He's afraid of his mother and won't be honest about his intentions with Ann. Perhaps part of him knows that telling her will unleash some fury he wants no part of. He attacks his father savagely when Joe's guilt is revealed, calling him lower than an animal. But after a night of thinking about it, Chris still can't bring his father to justice:

"I know what you're thinking, Annie. It's true. I'm yellow. I was made yellow in this house because I suspected my father and I did nothing about it… Now if I look at him, all I'm able to do is cry… I could jail him, if I were human any more. But I'm like everybody else now. I'm practical now. You made me practical." (3.122-124)