User blog comment:Read Books/Wondering?/@comment-5053045-20141101232653

I've been thinking about this a bit. I think the only way for it to be acceptable would be if the Konoha leaders specifically pulled him/her/them out of there before the massacre for whatever reason (albeit it would have had to have been a very important reason.)

Or, maybe, they could have been a test subject of Orochimaru's but with an underdeveloped Sharingan? That way, no one would have known they were an Uchiha, methinks. And, depending on their age, various different things could have happened to get them to land in or near Konoha.