Boo Radley is an albino.
When Scout finally meets him in person, he is described as being ghost-like, with very pale hair and skin. Scout, not knowing what albino is, would just assume this is because he stays inside all the time, rather than Radley being born like that. This would also explain why Radley is familiar with the doctor; he probably would have medical problems which often come with albinism like bad eyesight. It might also be partly why he lives such a reclusive life, as if he was an albino he would be easily identifible in a small town and rumours could spread easily about him, (especially in 1930's Alabama).
Bob's kids have different mothers.
Although Bob Ewell sexually abused Mayella, the story has never mentioned her being pregnant. So maybe she isn't the mother of the kids. Bob maybe had kids with various prostitutes.
- Except he doesn't seem like the sort of guy to take in bastard children who could potentially have had other fathers. Also, Maycomb doesn't seem like the sort of town that's swarming with prostitutes.
- Bob also doesn't seem like the kind of guy who can afford prostitutes.
- It's not mentioned because the narration is from young Scout's point of view and adults would have been careful to sweep that kind of thing under the rug and especially not mention it in front of a child. And Scout thought babies were dropped down the chimney or obtained from an island, she wouldn't have figured it out even if she'd overheard rumors.
Boo Radley is a War Veteran
One of the gifts that Jem and Scout find left behind by Boo happens to be a war medal. Assuming Boo Radley is in his late 20s or early 30s he would have been old enough to have fought in World War I. If he is a war veteran it would explain why his behavior is so odd, he is suffering from Shell Shock or what we now call Post-Traumatic Stress Disorder. Boo Radley giving up a war medal to these children shows how much he cares about them, he's reaching out to them with a symbol of the experiences that caused his trauma in the first place.
- In the movie it was a spelling medal (Jem: "They used to give these out at school before we were born.").
- It was also a spelling medal in the book.
Decades before the book takes place, Atticus Finch murdered a black man.
Atticus Finch, the man of morals, hates injustice. He especially hates when a white man abuses a black man. "There's nothing more sickening to me than a low-grade white man who'll take advantage of a Negro's ignorance." As a youth, he was an exceptional marksman ("Ol' One Shot") but for some reason he gave up shooting ("haven't shot a gun in thirty years"). According to Scout, he "hated guns and had never been to any wars" - which, if true, would seem to rule out the possibility of his aversion to guns being due to experience in war. Miss Maudie DOES say "I think maybe he put his gun down when he realized that God had given him an unfair advantage over most living things". However, perhaps as a youth, Atticus was racist - perhaps even a member of the Ku Klux Klan - and actually either directly murderered a black person himself or participated in a group murder (lynching). That could go a long way toward explaining both his especial hatred of white abuse of blacks and his strongly held belief that he was morally obligated to defend Tom Robinson and that he couldn't face his children if he didn't.
- It could have even been an accident. Nathan Radley fires off a gun when he thinks a black man is in his collard patch, and a neighbor advises him to shoot low and aim to kill. Atticus could have taken aim at what he thought was an animal.
Boo Radley has social anxiety
The intense shyness and fear of going out in public seems cute and endearing when Beth March
or Laura Wingfield
has it, not so cute when it comes from a young man in a small town.
Boo Radley is gay
And Miss Maudie saw fit not to mention it to young Scout. Him and the gang of young friends he was caught with might have been caught "experimenting," or in a part of town known for queer activities, or one of the kids may have just had a reputation. Anyway, it was the accusation (or even the suspicion) of homosexuality which drove the elder Mr. Radley to such an excessive abuse towards his son.
Link Deas hails from Hyrule
Atticus Finch stole the Triforce of Courage, so Link Deas chased after him and set up a business hoping to spy on him. However, He didn't anticipate the trial of Tom Robinson, and the two became friends.
Atticus Finch isn't actually Atticus Finch
In the later chapters, Atticus doubts his own values. He is doubting who he is, so why shouldn't we doubt who he is? There is a possibility Atticus isn't actually Atticus Finch, due to his mixed signals about morals and seemingly his lack of caring for his children. My theory is that he is actually a man named Tim Anderson.
Old Mr. Radley's abuse affected his sons in different ways
The rigid, strict lifestyle and belief imposed by the brothers' father could be a significant factor in molding the Radley brothers' characterizations. Old Mr. Radley, described as a foot washing baptist, was an authoritative man who believed pleasure is a sin. As such, Arthurs early home life would not likely to be a pleasant one. His fathers imposition of the lifestyle and belief could have met with opposition by both his sons, Nathan and Arthur. Both brothers reacted differently from their father's rule. It is possible Nathan strived to emulate his father and played as the behaving son to avoid the abuse by his father. While it would be more obvious that Arthur would be heavily negatively affected by his father's influence, Nathan Radley also was possibly damaged as he might have use the opportunity to move to Pensacola when he came of age to escape his father. Arthur in contrast took to rebelling his fathers rule by joining a trouble making gang when he was a teen to experience some freedom he was deprived of. Due to his passive personality, it is likely he was a tagalong in the gang and had little ability in resisting his punishment of forced isolation for his rebellion until the stabbing incident.
When their father died, Nathan was summoned to return to Maycomb to become jailer to his younger brother. Nathan could have resent his situation and possibly his brother for bringing him back to a place and lifestyle he was escaped from in the first place. His resentment might have resulted his decision in also abuse Arthur. As much as he like to think he had little common with his father, he is as much as his father due to him executing the same methods in keeping Arthur Radley locked up.
The combined abuse from his father and brother and the forced isolation definitely damaged Arthur's mental health. Arthur became withdrawn and reclusive and most likely acquired social anxiety or agoraphobia, which would prevent him stepping foot outside.
Boo Radley is dying of tuberculosis.
When Scout meets Boo, he does not seem too well. We see him coughing and sweating, which are some of the symptoms of tuberculosis. As the characters are generally modeled from real life counterparts and as Boo's real life inspiration, Alfred Son Boulware, died from tuberculosis, it could be concluded that Boo is also suffering from the disease due to his symptoms and the fact that Dr. Reynolds's familiar with him. When Scout states she never saw him again, it is likely due to his death shortly after their meeting.
Boo's brother was trying to protect him and the kids.
It's clear that there really is something
wrong with Boo - this is 1930s Alabama. Even without an abusive dad, a young man with mental or emotional issues certainly would not have gotten the help he needed. It's also mentioned (though not from a very reliable source) that Boo once attacked his father with no warning.While that could be an understandable reaction to years of abuse,
it could just as easily have led his family to assume Insane Equals Violent
. Boo's brother apparently got out of the house as soon as he could and was away for a while - all he knows about Boo is what his Abusive Parents
choose to tell him. And Boo is
capable of violence, though on screen only to Asshole Victims
. So from Nathan's perspective, when his mentally ill brother starts interacting with neighborhood kids, that is a big red flag - who knows what Boo knowingly or unknowingly may do to the kids if they pester him or scare him by mistake. His actions are misguided, but well meant efforts to protect Boo from himself.
Atticus and Calpurnia were in love.
Hear me out. Bear in mind that this is 1930s Alabama, and interracial relationships are severely discouraged if not outright banned. Atticus, a widower, never remarried (Go Set a Watchman, if one considers it to be the events long after TKAM, confirms this) in a time when it was expected for a widowed father to find a new wife posthaste. Atticus was respected and couldnt risk losing the towns trust over Calpurnia, so he hired her as his housekeeper and caretaker for his children. The role Calpurnia took on wasnt that different from what a stepmother would do; Atticus allowed her that free rein. GSAW makes it even more clear after Calpurnia left the home - Calpurnia was extremely bitter and wouldnt even have a conversation with Scout. Why? This explanation makes the most sense - Atticus was afraid to come forward when their relationship. Calpurnia wanted him to be a real couple and a public face of civil rights in their town; Atticus felt he couldnt do it and still practice law. So she got angry and left, and his bitterness made him turn against the people who reminded him of the woman he used to love.