what began the misery of the Radley house

I think the Radley's were always a little off to begin with. I suppose the specific event would be when Arthur (Boo) as a youth fell in with a bad crowd. One night they were drinking and vandalising a little; they were having some teenager fun. The boys get arrested. Arthur's friends get sent to reform school, which according to Scout was not so bad, and Mr. Bradley promises the judge that (if he let Boo go) Boo will never bother the town again. Mr. Bradley’s solution for this was to lock Boo in his house forever! That was not a healthy move for anyone in that family.