Are certain dog behaviors, like fear or aggression, genetic?

It may be a little bit of both. I believe that a lot of aggressive behaviors can be prevented by the way the puppies are raised, but there are possibly heritable traits that could be passed along with breeding. I would avoid breeding aggressive dogs.

No, I'm afraid not. Aggression towards strangers is largely a genetic trait - some dogs are quite friendly with people, while others are not. With an otherwise friendly dog, you would need to pursue professional protection training if you want your dog to show aggression towards strangers in certain circumstances, since it sounds like this isn't his natural personality.

There are many factors in what causes a dog to bite. Abuse is certainly a contributing factor, along with other factors, such as the immediate situation, breed (not always pit bulls!), if a dog is cornered by someone or something, territorialism, protectiveness over a person or something like a litter of pups, aggression over food or objects. Many bites occur simply because someone ignores or in unfamiliar with the warning signs of anxiety in a dogs, such as licking the lips, eyes widened so the white is visible (called 'half-moon eye' or 'whale eye' by some), excessive panting, yawning, freezing in place, staring or even looking away. Failure to recognize these and continuing to interact with a dog, no matter what the intention, can result in being bitten.

Yes, all dogs can be trained. It's important to focus on daily exercise and training. Some dogs will have a very high exercise requirement and may require 1-2 hours a day. A tired dog is generally a better behaved dog. Also, you need to figure out if this is true aggression or simply mouthy play. Some dogs like to play rough and if they are not taught appropriate boundaries, they can accidentally hurt their humans. True aggression is more worrisome. Canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not familiar with reading canine body language and training. Because of this, I recommend to work with a professional trainer. Researching on your own will also be helpful. Familiarizing yourself with canine body language and dog training can help you to recognize what your pet is trying to say. You can find many books written on the topic and there is a trainer named Victoria Stilwell who I think is particularly helpful. Best of luck.

Fear and aggression are both often due to underlying fear and/or anxiety. Working with a trainer will help you learn how to correct behaviors in a way that doesn't exacerbate anxiety or fear. It may be helpful to discuss anti-anxiety medication with your veterinarian as well. What you are describing is not normal, but working with behavior modification techniques and possibly with medication could be very helpful. Best of luck with him. https://www.petcoach.co/article/6-common-myths-about-dog-aggression/ https://www.aspca.org/pet-care/dog-care/common-dog-behavior-issues/aggression

Canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not familiar with reading canine body language and training. Because of this, I recommend to work with a professional trainer. Researching on your own will also be helpful. Familiarizing yourself with canine body language and dog training can help you to recognize what your pet is trying to say. You can find many books written on the topic and there is a trainer named Victoria Stilwell who I think is particularly helpful. Certainly male dogs who are not neutered are more prone to fighting and aggression. Neutering him may help but it will not likely solve all the problems. Best of luck.

Leash aggression is actually pretty common. When an animal feels threatened or scared they need fight or flight. When they are on leash you have now removed the option of flight so you are way more likely to have a fight reaction and this is why you are noticing this on leash vs. off leash. This is something that needs assistance of a professional trainer, working under the dogs threshold to address the issue. You can see varying amounts of improvement depending on the severity of the case but it's going to take a lot of work and commitment on your part. Please seek help from a qualified professional. Not addressing this issue now will only make it worse and harder to deal with later.