No "childhood event" at all, it's just the chemical reaction to the combo of him being attracted to women + feeling superior to the people around him + having a degradation kink. I think you have to keep in mind Cy is self-aware about his misogyny– he's aware the scientific studies out there prove women aren't any less competent or smart than men. But because he enjoys degrading Lynn, he joyfully leans into his misogynistic tendencies because it'll get both of them off, and because traditional gender roles are his vision of a good D/s dynamic. Engineering is also a very male-dominated field, so the culture is pretty different from your average work environment. Some of Cy's more unironic biases probably come from there.