So, if I understand you correctly, the premise is that, while the brave went off to war and all died (every single one of them), the cowards (whose cowardice also apparently conferred them with hyper sexuality) helped themselves to the wives of the brave, thus causing a baby boom of fresh young cowards?

Interesting theory. Completely missing the fact that sex among couples increased dramatically just before shipping off to war, however. I'm also wondering which study you're relying on to state that "bravery" and "cowardice" are genetic traits passed on exclusively via males.