Why do Jem and Atticus agree to keep the blanket for the time being? Why not take it right back to the Radleys? What does this indicate about Boo’s family life?

Atticus and Jem feel that returning the blanket would cause unnessary attention for Boo and possibly get him into trouble. Although I don't believe Atticus made this decision based upon Boo's family, but rather worry over Mr. Nathan's actions.

“…Mr. Nathan put cement in that tree, Atticus, an‘ he did it to stop us findin’ things—he’s crazy, I reckon, like they say, but Atticus, I swear to God he ain’t ever harmed us, he ain’t ever hurt us, he coulda cut my throat from ear to ear that night but he tried to mend my pants instead… he ain’t ever hurt us, Atticus—” Atticus said, “Whoa, son,” so gently that I was greatly heartened. It was obvious that he had not followed a word Jem said, for all Atticus said was, “You’re right. We’d better keep this and the blanket to ourselves. Someday, maybe, Scout can thank him for covering her up.”