Pretty much everyone in All My Sons has a secret. Even as they tell jokes, drink grape juice, and dream of dancing, the characters vigilantly protect damning information that, if revealed, will destroy their lives. Part of self-protection means placing the blame elsewhere, creating diversions. You shift the blame to an old neighbor, your son, your parents. All the forced fun of suburban family get-togethers covers a well of guilt and shame that inevitably boils to the surface.
In All My Sons, the suburban community's strong capitalist values enable Joe Keller to get away with murder.
Chris poses as an idealist to distance himself from his father and subtly deflect blame from himself.