Your alcohol has been contaminated with congeners (fusel alcohols) during distillation. This occurs when you continue collecting distillate even after the "tails" are being condensed.These oily-like substances are soluble in highly-concentrated alcohol and are then invisible but if the alcohol is then diluted, these substances are no longer entirely soluble in the dilute solution and form an emulsion that makes the alcohol appear milky.Re-distillation is the way to remedy this problem.Alternatively, the water used in your fermentation or dilution of distilled alcohol, may be very hard and some of the chemicals may precipitate out and form the milky or cloudy appearance.The remedy is to use better-quality water such as water purified by the reverse-osmosis method and which can be bought at many grocery stores or specialized water stores.