I've always wondered about my family like that because I could not be more different from them....physically, mentally, and personality wise.... (thankfully)Funny, that. I know a fellow who was different from all of his siblings, short, swarthy & stocky to their tall, slender blonde. His father treated him horribly. His Mom doted on him. After both passed, and aunt clued him in on an old story ... and he he acted on his hunch. And that's how I met my eldest cousin! True Story!!!
No telling what kind of skeletons I might uncover if I decide to do an ancestry test.