As his natural meanness, Mr Radley's aloofness is voluntary whereas Boo has been constrained by his father to stay in the house. A boyish prank (temporarily locking up a man in an outhouse) could have turned in Boo's favour, for the other boys involved were sent to a local technical school to stay out of trouble and eventually got a good education. Mr Radley is too proud to accept the county's terms of "punishment" and struck a deal with the sheriff: if Boo is not made to go to school, he would keep him at home and out of sight. And that's what he does.
In the beginning Boo is more a victim of his tyrannical father than of society. However, the wicked gossip circulating around Maycomb only increases his estrangement as local people add on to an already sordid story. Boo is accused of nocturnal rambling, eating raw bloody meat, and being a peeping Tom. No wonder his reclusion becomes permanent.