I've had the anery gene pop up in several projects that I would have prefered it not to.
I've had the Motley gene pop up in a pair that totally surprised me.
Many normal or single mutation animals are the result of other projects or have ancesters from genetic projects. Odds that you might match up an amel or anery are pretty good, they've been around for a long time. Other traits like Caramel and Lavender will become more common as the genes become more wide spread.