Answer
Parthenogenic parents are female since only they have the egg, the cell which is large and rich enough to support early development. Sperm are basically nuclei delivery vehicles and do not have all that is needed for development, even if diploid.
Work Step by Step
Review the differences between sperm and egg. Sperm are like a chicken egg in a carton; eggs are like all of the ingredients for an omelette waiting to be cooked. (An imperfect, but useful analogy.)
