Want to learn something about people? Start by studying (really smart) dogs. A lab proposed this as a way to determine why one person ended up "a Milquetoast and another a bully."
"They chose to work with dogs," we say, "because, as you've probably noticed, they act a lot like human beings." (Not sure I would conduct scientific experiments based on how similar we are, but OK.) By seeing how exposing one to different situations during its development, researchers tried to determine how it would behave later in life. A brother and sister dog, for example, could act much differently than expected based on how they were treated growing up.
One test involved regularly yelling at the dog while brandishing a yardstick. Surprise! That could make you timid.
From the article "Science Tries You Out on the Dog."