Once an animal inherits the genes necessary to be a BEL, will it always only be a BEL regardless of what else it inherits? Or if other genetics are added to the mix (ie spider genes, pastel genes, etc.) will something new come out?

I know there are tons of combos involving the lesser gene out there, but does the butter gene have the same potential? Or is it mainly used for making BELs.

Thanks,
Dennis