Rooster prediction at 3 weeks - Light Sussex??

[paddyro]

I hatched a mixed clutch of 9 eggs a few weeks ago, with breeds including Wyandottes, Light Sussex, Araucanas, Americanas, and Marans. I'm wondering how much of a conclusion one can draw from behavior? Both Light Sussex chicks are larger, feathered out earlier, are bossy, and do a lot of "chest bumping" with each other. They herd the other chicks as well at times. Is this a Sussex trait or am I seeing Roo behavior??

If how the chicks interact with one another is any prediction of sex at this young age, I'm guessing the following (and will report as they develop):

Mathilda - Wyandotte (1) - sweetest in the world. Very quiet, curious. My guess - Girl
Lemon and Brody - Light Sussex (2) - Bossy, bossy, bossy! Big birds. My guess - Boys
Pepper (Ameraucana) - skittish, quiet, smaller - girl
Glorious (Ameraucana) - skittish, loud, a bit more aggressive - boy
Up and At 'Em (Splash Marans) - big, bold, friendly - boy
Josephina (Black Marans) - quiet, aloof - girl
Hippy (Araucana) - LOVE THIS BIRD - gregarious, bold, challenges the Sussexes - Boy :-(
Hoppy (Aruacana) - quiet natured - girl