Why was McCandless able to develop such affectionate relationships with older people like Jan and Bob when his relationship with his own parents was so tense?

I think that Chris longed for a relationship with elders but used his parents as part of the reason that he turned his back on society. In blaming his parents, especially his father, for society's woes, Chris was able to divorce himself from his old life. Once "on the road" he wanted the company of elders. Perhaps he was compensating for a part of his life that he lost.