I will not have a son. Although his laughably under-planned attempt to usurp power would easily fail, it would provide a fatal distraction at a crucial point in time.
For some, children are great. They provide a warmth and happiness that can't be fulfilled by any other means known to man. They allow you to carry on your legacy, even after you have passed.
But you're an evil overlord. The everlasting empire you will create is enough of a legacy. And what happiness can a child provide that your vast realm cannot provide?
So keep your harem with a healthy supply of birth control, export any ladies you get pregnant to other realms, and considering enjoying the company of fellow men in your bedchamber and see if it's for you. If you happen to be a lady overlord, the same rules apply - maintain your birth control, fill your nights with fellow ladies, and keep an open line to some orphanages/adoption agencies should a little accident happen.
Part two of advice for offspring is up next!
Exporting pregnant lovers to other realms and sending accidents to orphanages sounds like a good way to get surprise usurpers with daddy issues in a couple of decades.
Your overlord has gone soft...