A question about selective breeding.

Right now I’m eating a “Grapple” (grape-ul), an apple marketed because it tastes like a grape, which it kind of does (it’s really more of a natural apple meets grape soda flavor, but it’s still good). I’ve also seen websites that sell Geraniums that smell like roses, apples, coconuts, apricots, etc. And I’ve had a mint plant that smelled like lemon. In my very basic understanding of genetics, a grape vine and an apple tree don’t cross breed (wouldn’t that be like a giraffe and a gnat?), so how do plants like this come to be? Do botanists take a whiff of a plant and say “Hey this smells like lemon kind of…” and then a whiff of another plant of the same species and say “Hey this one sort of does too!” and then cross pollinate the two to get an even stronger lemon scent? Or is there some easier method?
(Posting this in the hopes that at least an amateur botanist is a member of the board)

From what I’ve read on the subject, often shoots of the plant that have the desirable trait are grafted onto the stock of a genetically similar plant. Which is why you don’t want to prune back the roses too far.-+

The Grapple has nothing to do with genetics at all. From here

Regarding your other examples, there are many basic plant compounds that are found in a range of different families. It is quite possible that selective breeders could enhance these chemicals to bring out a certain smell or taste that is normally only found at low levels in the original plants. In particular, the Scented Geraniums have been developed through cross-breeding and selection among a a variety of original species.