] There is much we don't know. I've wondered if, for example, he might have stayed with his mother's people after she died, which was not uncommon in those days. The family left Stanhill 11 years prior to the action of the story, but there is no specific mention of John coming to Norland with them at that time--it says only that old Mr. D."received into his house the family of his nephew." But John not being raised with them would partially explain his lack of feelings for the girls as his sisters! If he were raised in the same home as them from the age of 7 or so until he married, it is very hard to understand indeed.

From Chapter 12:
"You are mistaken, Elinor," said she warmly, "in supposing I know very little of Willoughby. I have not known him long indeed, but I am much better acquainted with him, than I am with any other creature in the world, except yourself and mama. It is not time or opportunity that is to determine intimacy: -- it is disposition alone. Seven years would be insufficient to make some people acquainted with each other, and seven days are more than enough for others. I should hold myself guilty of greater impropriety in accepting a horse from my brother than from Willoughby. Of John I know very little, though we have lived together for years; but of Willoughby my judgment has long been formed."

She says they lived together for years, so I think he probably lived with them until he went off to school and then married. Since she specifically mentions 7 years, I wonder if that's how long he lived with them?