I have found that aggressiveness goes both ways....it CAN be passed down through the genes, but it can also be an environmental factor as well. So until it is truly determined that you have aggressive quail, you don't really know if they are aggressive or not. Lots of things stress birds out and cause them to turn on their flock mates. When these stressors are removed, usually the birds return to their normal state. However if you really do have aggressive birds, it is very possible to pass this gene on down the line.