The wife and I were just talking about this because we were smoking some Pineapple Express and she said, "How do they make it taste and smell like this??" Me being a scientist, said, "I have no idea, but I like it!!!!" lol
I have a feeling it has a lot more to do with similar terpene profiles w/ fruit and other vegetation.. Theoretically, there are only a set number of terpenes so I'm sure there are many things that can share them in their lineage.. Perhaps some of these strains inherited something from nearby crops and thus have those properties?? Hard to say, as I'm not a botanist or biologist; merely a human physiologist who enjoys some seriously dank, home-grown botany lol