As the author of a JV biography, such as it is, I have suffered the usual temptation of biographers, to try to interpret the subject's story-telling choices in terms of his earlier family experiences. My conclusion is that Vance is too "distanced" a writer to do anything as superficial as write stories in which the protagonist dislikes his father or older brothers because that's how the author feels.

If anything, JV writes the opposite of his personal experiences. As noted, his father figures are admirable, his protagonists are single children rather than the middle child of five, etc. I think that for every suggestive situation in one story, you can point to another JV story in which the situation is entirely different.

Frankly, there are practical writing advantages to having protagonists from small and/or disrupted families, aside from the fact that the disruption may provide the protagonist with purpose, a la Gersen: in an adventure story, entanglements with parents, siblings, etc. are distracting and slow the action. You can't take time to attend the family Thanksgiving get-together while hot on the trail of interstellar evil-doers. As in Jaro Fath's case, his adoptive parents were useful in the early chapters during Jaro's formative years, but they needed to be blown away when the time came for Jaro to run free and bring villains to justice, as it was necessary for him to kill his own mother in order to create the basis for the plot.