Some of it they are born with, some dogs, even dogs of the same breed, have stronger drives for some game than others, different talents. Hey I'm flexible, if the dog wants to hunt Hare, I'll hunt Hare.
I've used a long leash hunting Boars in the late morning. Depends on the time of year, when the squeakers are young the Sows run the Boars off. People say Boars will eat squeakers, older Sows are far from stupid. Well anyway, the Boar often trail behind the sounder and may bed down well short of the favorite bedding area. I sometimes trail a sounder late morning after it starts to heat up a bit and have come across Boar bedding in some brush. Right where the brush ends and the grass begins, often in ditches or low spots.
My dogs grew up chewing on Hog ears. Born hating Fox, took me awhile to discourage my Weimaranar from tearing Fox to pieces. The gun dogs are usually natural pointers. Had one that was a natural retriever, another was a really good tracker. Funny about that one that was an iffy retriever, he once dove under water going after a wounded Goose and stayed down there so long I thought he had drown, came back with the Goose. I think his retrieving flaws were mine and not his.
You can see it in this picture, holding that Fox and not tearing it to bits did not make the dog happy.
I usually take the pups where the game is I want to hunt, if they have any prey drive at all they will get excited and chase. True hunters don't take a whole lot of encouragement. A whole lot easier if you can take the pup out with an older dog. But taking them out with an older dog has it's disadvantages, it may teach the young one it's bad habits.
My daughters German Shorthair mix was a born bird dog, but would take out after Hogs. A good retriever. Like I said I tend to go with the flow, I hunt what they hunt. He was also very very fast. I really wanted to work him as a Lurcher or Hound but was always afraid I might ruin him.
Your job is to figure out a way to communicate to the dog what you want and/or adapt to it's quirks. Sometimes you get paired up with that magic dog and it just clicks, you can teach then anything.