Not a biologist but I don't think it has to do with how much the genes get expressed but rather that they do get expressed and in bad times (pesticide) they're really good and look like they dominate (in that you only need one copy to get the expression/benefits) but in good times (pesticide free) they don't introduce that much negative cost and so you need two copies for adverse effects.
Environment modulates epigenetic expression so that, at times, recessive genes actually get expressed more?
Not a biologist but I don't think it has to do with how much the genes get expressed but rather that they do get expressed and in bad times (pesticide) they're really good and look like they dominate (in that you only need one copy to get the expression/benefits) but in good times (pesticide free) they don't introduce that much negative cost and so you need two copies for adverse effects.