Homozygous. The really odd thing about the hidden aka daddy aka dilute aka sib mutation is that not only do the hets look normal (unlike the het lessers which are visible lessers) even the homozygous hidden remains normal looking (i.e. "hidden"). So it's a mutation you would just have to track through breeding results and/or parentage. One animal you can be sure doesn't have it is a normal lesser because if it did it would be a platy. Also, since it's apparently a mutation of the same gene as lesser/butter, mojave, phantom/mystic, Vin Russo, and mocha keep in mind that any one snake only has two of these (or any) genes total so if it's already say a mystic potion (mystic + mojave) it doesn't have room for a third copy (like hidden or even the normal version of this gene).