Maybe I just got lucky or my birds are just that much more awesomer than most

but I see all the threads about people integrating there babies with each other and older birds and I wonder how my birds survived. I bought 4 @ 1 week old & 3 @ 2weeks old. When I bought them they were all thrown into the same box for the ride home (the place I bought them from had all different breeds in separate brooders so they knew what was what), then when we got home they were all put into the same brooder. Never had any problems of them trying to kill each other or really even picking or pecking or general chicken abuse. The 4 younger ones did get stepped on a couple times by the bigger ones but that's about all that happened.
I think it just depends on the birds. I routinely mix different ages. Right now, my turkey brooder has a 5 1/2 week old, 3 4 week olds, a 3 week old and soon will have 4 1 week olds in there with them. I've been mixing ages since I started. Of course, I always supervise to make sure they get along before leaving them alone. Out in the main coop I have 11 that are a year and a half old, 7 that are 6 months old and 10 that are 8 weeks old and they all get along lol