I guess the story evolves from week to week. The last I heard, the hidden gene you referred to is what made them citrus or not. It isn't a straight forward thing to be sure.
I'm sure he is enjoying his project getting some attention. Here is some of my citrus stuff from last year. The top picture and also others clutches is what inspired the whiteout name. The bottom two pics are how they colored up after a couple of months.

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