Larry Mcmurtry said this quote

But, if one cuts more deeply, the lonesome dove is Newt, a lonely teenager who is the unacknowledged son of Captain Call and a kindly whore named Maggie, who is now dead. So the central theme of the novel is not the stocking of Montana but unacknowledged paternity. All of the Hat Creek Outfit, including particularly Augustus McCrae, want Call to accept the boy as his son.