“Dune” and “The Walking Dead” actress Alicia Witt has broken her silence concerning “misconceptions” about her parents’ deaths after the couple was found in their Massachusetts home late last month. Robert Witt, 87, and Diane Witt, 75, were found dead on Dec. 20 with no obvious signs of trauma. Though there were reports about the couple having issues with their furnace and subsequently using a heater indoors, no abnormal levels of carbon monoxide had been identified at the time. Witt, 46, took to social media Tuesday and, in a heartfelt post, appeared to confirm that her parents had indeed suc…