So, you could date the Windsor family business from 1399, when Henry was crowned, although some take it back to the medieval foundation of the Duchy, before it united with the monarch.
When you look at the origins and histories of these royal families, you realize that they basically are descended from a bunch of warlords essentially like Mafia godfathers or Arab sheikhs. Murderous, backstabbing, conspiratorial trash. They lived off of taxes on the lower orders and spent their time riding to the hounds, screwing harems of mistresses, and fighting other nobles for power.
Thanks; I’ll just point out that each of the so-called royal houses (apart from the current one) has died out, going extinct. The most recent extinction was that of the House of Stuart, which ended with Queen Anne, and of course had a few little bumps in the road (the Glorious Revolution, the English Civil War / Protectorate).
I recall reading years ago that all the kings and queens of England have been descended from Alfred the Great, King of Wessex.
http://www.britroyals.com/royals1.htm