I have a kind of wacky theory I'm trying out. I really wanted a fairy dragon but I kept getting fruitfuls. So looking at the air x forest combo, it seems possible to me based on their coloring that fruitful=green/green/yellow and fairy=green/yellow/yellow. If you follow this theory, it could make sense that you get more yellow genes from a higher level air dragon and fewer green genes from a lower level forest dragon. So I bred a level 9 air with a level 4 forest, and with an 8hour breeding time I'm thinking I have a fairy egg on my hands.
Obviously this could be a total fluke, but I am going to try to replicate this with the other rare breeds. I am thinking serpent=blue/green/green, mindvolt=blue/yellow/yellow, wild=green/green/red, eagle=yellow/yellow/red.
Anybody who wants to try this line of thinking and pitch in data is most welcome. Also, tinfoil hats are welcome too