"Fair, chaste, and fertile," was such an odd way to state the requirements, because if a woman is chaste there's no way to know if she's fertile. Still, as creepy as the virgin requirement was, I understand the need to make sure the first born, at least, carries the DNA of the Prince and not some recent boyfriend. Because carrying that bloodline is absolutely the one and only thing that sets them apart from the scullery maid in the basement and qualifies them for all that prestige and perks. It's so weird to think that all the living in palaces and being curtsied to and prime ministers having to suck up to, is based on one of their very distant ancestors doing well in war a thousand years ago.
I get a kick out of the monarchy in a celebrity watching way, but it goes against everything I believe regarding visiting the sins (or virtues) of the fathers on the sons. Imagine if we Americans met someone at a party who could prove he was a direct descendant of George Washington and we all started bowing and scarping and set him up in the White House with a huge allowance for life. No. We would say, "Really? Cool," and go back to our conversation. Someone like Princess Margaret, who thinks she deserves all that deference based on being someone's sister, would never understand that.