Keep in mind I am a first time chicken owner so you might need to take my thoughts with a grain of salt, but I think their being friendly or not has mostly to do with how much time is spent with them as they are growing up. Yes, their basic personality is there no matter what and some leghorns are just more stand offish than others no matter how much time you spend with them but spending a lot of time with them helps make them all friendlier/calmer. We also have barred rocks, polish, and silkies and admittedly all of those breeds are calmer than the leghorns but our leghorns are not flighty like I figured they were gonna be based on some descriptions I've read about them.