The genetics behind dog behavior remain an open field, and genes involved in behavior aren’t as well-profiled as, say, coat color genetics… but that’s what makes behavioral genetics very exciting, too!
I might suggest reading about this study on Labrador Retrievers for a good example of behavioral genetics:
The original scientific article is here:
In short, Labradors with deletions in this POMC gene have higher rates of obesity (health and behavior-related) *and* Labradors with this variant are overrepresented in service dogs (behavior-related). The hypothesis behind this being that POMC influences food motivation, and that dogs who are more food motivated will work harder for a reward (great for training!)