I agree that in reality it is often impossible to predict someone's actions, if you are going to tell them your prediction. That is why it is perfectly possible that the situation where you know the gene is impossible. But in any case this is all hypothetical because the situation posed assumes you cannot know which gene you have until you choose one or both boxes, at which point you immediately know.

EDIT: You're really not getting the point, which is that the genetic Newcomb is identical to the original Newcomb in decision theoretic terms. Here you're arguing not about the decision theory issue, but whether or not the situations involved are possible in reality. If Omega can't predict with certainty when he tells his prediction, then I can equivalently say that the gene only predicts with certainty when you don't know about it. Knowing about the gene may allow you to two-box, but that is no different from saying that knowing Omega's decision before you make your choice would allow you to two-box, which it would.

Basically anything said about one case can be transformed into the other case by fairly simple transpositions. This should be obvious.