No, I think they said it was artificial. A previous employer took a potion/medicine that has now caused the red dot to appear on everyone of imperial bloodline. If you are of imperial bloodline, you will have the red dot. Anyone who doesn't have it, is not of their bloodline. This is why, although he looks different from them, they all know with certainty that the ML is of imperial bloodline. When they say it's artificial, they mean the red dot appearing isn't caused naturally by their bloodline or for any divine reason. It was caused by medicine a previous emperor took. The only thing the red dot can't due is determine paternity. It can say you are an imperial member, but it give no indication of how. That's why they said the baby could be one of his brothers. I hope that helps.

I can't imagine how daunting the whole situation has been for the empress. She had a story you could write fairytales about, but because she hasn't given birth in the 9 years she has been married, she has to accept her husband sleeping with other women. She also has to be present and appear supportive when these women give birth?! That's enough to make anyone depressed or bitter.
The emperor could have had the decency to keep it in the palace. I understand that the pressure to have an heir and secure the throne must have been intense, but why was he outside the palace with his pants down? Messing with a woman who has many lovers when you have a beautiful wife at home is crazy. I will never understand the mentality of men and women who do that.