If I leave the skin on my potatoes will they turn dark?

No. What discolors potatoes is when they’ve been cut raw, then exposed to the air. The potato (being a living organism) will attempt to ‘heal’ the exposed surfaces. Another way that potatoes discolor (durn dark) is when they have been kept too cold (below 41 F) for too long. The time for this to occur varies, but suffice to say, store potatoes cool, but not cold. If stored too cold, the potatoes’ starches within convert to sugar, making for an overly-sweet potato and the cooking chemistry is altered. This process can be reversed (called reconditioning) by transferring chilled potatoes into an ambient (room temperature) environment. It may take a week or even longer for the high sugars to ‘burn’ off. Test for high sugars using diabetic strip tapes (found in most pharmacies, or online). Test by touching the test pad to the cut potato surface, then compare the tape to the scale on the test jar. The darker the tape, the higher the sugar level.