Note that it's a memoir. By definition, a memoir is "This is what I remember".

Some of the names have been changed to protect the innocent. And maybe the guilty as well.

Also keep in mind that it is human nature to never let anything as inconvenient as facts get in the way of a good story.

With all that as background, Look Me In The Eye, by Burroughs' brother John Roberson reads very similarly. So you're looking at fictionalized truth or an impossible (based on my extensive interactions with people with ADD) conspiracy.

Note also that the estate of Burroughs' foster family sued him for libel. They settled out of court (so we can't know what they agreed to) and future editions of the book say that although the foster family remembers things differently, this is what Burroughs remembers. Burroughs said he felt vindicated by the settlement.