Philip, your sweet peppers and jalapeno peppers could have crossed -- but it wouldn't have affected the fruit that you harvested; the cross would have shown up in the offspring grown from the seeds of those peppers. If your Italian peppers were the result of a cross, it would have been a cross between plants that produced the seed that you grew out (or that someone grew out to produce the plants that you bought). There can be a LOT of variation within any given variety of vegetable.
