Possibilities

So much difference between the two dogs.   Sonya drinks water, normal water like it's going out of style while Wendy turned her snout up at all but bottled water and eau de toilet.  Sonya has dug trenches across our backyard while Wendy was prissy and never stooped to dig a hole in her life.  Sonya buries the remains of rawhide bones between couch cushions while Wendy never had anything left to bury because Sonya is a picky eater who always leaves some kibbles in her bowl while Wendy wolfed down not only her kibble, but anything else that came with her purview, even mustard. 

There's more. Sonya is clumsy on the stairs. frequently falling halfway down, while Wendy zoomed up and down like a pro.  Sonya, even without a leash, sticks around when Husband and Fio take her outside, and she never pushes through the partly-open door to escape, like Wendy did.  And Sonya is more docile at Puppy Training, while Wendy was more--uh--willful.

It's all in the genes.  And again, if dogs behave differently because of their heritages, shouldn't we understand that's what's going on with us?   Even close relatives has wide genetic possibilities, some of them not too nice.  That's where we hope  the nurture comes in.

After all, sweet Sonya is the same breed as Cujo.