When is a wedding a real Royal Wedding? Arguably when both bride and groom have real Royal connections. But due to the chronic world shortage of eligible princesses, Today's nuptials are just another example of how the Royal genes have been diluted. The Duchess of Kent was married back in I961 - the first non-royal to walk up the aisle for more than a hundred years. Katharine Worsley, as she then was, came from a posh background but was no princess. Royal duties took their toll. These days she is something of a recluse, works as a music teacher and prefers to be known as plain Mrs Kent. Or take the former Duchess of York, Sarah Ferguson. Fergie was a commoner and proud of it before she married Prince Andrew, second son of the Queen. She may have lapped up the lifestyle, but she never really cut the mustard at the Palace. Scandal pursues the couple to this day, even though they divorced several years ago. The Countess of Wessex hails from equally humble stock - Sophie Rhys Jones was the daughter of an automobile salesman before the Queen's youngest son, Prince Edward, swept her off her feet. Their marriage has survived despite a tabloid exposee of how Sophie's PR company tried to market the royal link. The Queen's sister, the late Princess Margaret, searched in vain for a suitable prince, but fell in love with an Air Force officer. Trouble is he was a divorcee and the Royal Family wouldn't allow them to wed. So she teamed up with the photographer Anthony Armstrong Jones. He said "I do" and became Lord Snowdon. But this one ended in tears and divorce, with difficulties on both sides. The dearth of suitable suitors is a problem for our Royal family's European relatives too. Spain's heir to the throne, Prince Felipe, married a divorced TV anchor lady, and Norway's Crown Prince Haakon got hitched to a single mom. Prince Frederik of Denmark tied the knot with a girl he met in an Australian bar. Prince William's father, Prince Charles, is now married to the Duchess of Cornwall. Camilla isn't really royal either- though her great grandmother was mistress to his great great grandfather -- something that evidently runs in the family. Charles, of course, was famously married to Diana - another non-princess - until they were famously divorced. But this is hardly the time to remind ourselves of past Royal difficulties. We'll all be watching today's wedding and wishing William and Kate the very best. This is Ed Boyle for CBS News in London.