krakauer and other have speculated that mccandless was estranged from his family because of his relationship with his father. what was his family life like? does it explain his later behavior?

I don't think his family life fully explains Chris's behaviour. Chris was very upset when he found out his father was having an affair. This helps explain his animosity with father but doesn't explain his complete separation from family. Chris was supposedly close to his sister but even the few post cards he sent her eventually stop.