Nora, I think it’s safe to say both you and your husband win the argument. Very little in life is black and white, as I’m sure you already know. In behavior, we can usually make the argument for both genetics/instinct and learning impacting behavior.
I saw baby goats born the other day. Instinct told them to sniff and nudge mama for milk. But, they had to learn which side of mama the milk would come from! They explored her until they found the “faucets”. The first few days, they did a lot of suckling between her forelegs, which did absolutely no good, but each day they got a little better at finding the winning location. Genetics/instinct- suckling; Learning – location.
Meanwhile, back at the fence, dogs love high arousal chase games (instinct/genetics) as it is deep within their genetics to run after things. It’s part of the predatory sequence. It’s also highly rewarding to run and bark, which is the learning component. Each time your dog practices this behavior, the behavior is strengthened. Some dogs even start noticing precursors to the sequence of events, like time of day or the sound of the other dog being let out, and start running and barking before the other dog arrives at the fence.
Both you and your husband are right. 🙂 Does this sufficiently answer your question?
@NoraRuiz