G'day Jake,
Every year we get a few variegated seedlings from our breeding programme.
I have found that we can predict the occurence of variegation if I use a strain from a European source as pollen parents.
We generally consider them to be the product of a virus infection and immediately remove and destroy them.
I have ceased to use the strain that produced them for this reason.
Many of our Japanese cutomers are aghast at this practice because they value such variegations highly, however I feel thaty I'd be remiss in my duty if I allowed them to sneal through the system and be sold or to sell seeds from the infected plants.
Regards
John