Heck, this is nothing new. Animal breeders have known about this stuff since forever.
For example, this is what dogbreedinfo.com has to say about the "Labradoodle": FAULTS: Yappy, highly strung, dominance/aggression, fearful/timid, aggressive toward other animals. Dogs showing any of these behaviors should not be bred.
IOW, you assume that the personality traits are inherited, and you take animals with bad traits out of the gene pool.
This has implications beyond animal breeding, if you take a good look at our inner cities. The "bad boy" gangbangers are fathering more than their share of babies...
That in the beginning the "domesticated" animals may have selected themselves by surviving because of human activity, like the wolves surviving on human waste/refuse, and humans didn't start from scratch when they began breeding animals.
That there may be some physical appearances that are linked to passivity, like white/spotted appearance and cowlick positioning.
That humans bred animals for traits they wanted is old news, but the two things above were new thoughts for me.