@Jens_Rasmussen >There is plenty of possibility for a cowardly parent to have a brave child.
This is because Europeans are very outbred. They have a high diversity of genetic alleles and are heterozygotic in most of them.
Regardless, not everything is AA bb Mendel type shit, when you filter brave people your population will become cowardly over time. This is not really up for discussion. It's the basis of evolution and animal breeding.
The filter wasn't 100%, obviously. Many returned from war, brave and strong people are more likely to survive than draftees, and so forth.
Evolution mostly works by very loose filters over long times, although the ones we are talking about started around the time of the industrial revolution, which is quite fast in genetic terms, even if not immediate.

>Things like values and preferences can be instilled in a lot of people
I think this is called Agreeableness and it's one of the big 5 traits. Those are heritable. Ability to be "trained" was bred into people like it was into animals.