Heir ProblemsAs Bieber Slams William's Hair, How The Prince's Bald Spot Has Grown - In Pictures!Tom Sykes08.08.12Heir ProblemsAs Bieber Slams William's Hair, How The Prince's Bald Spot Has Grown - In Pictures!Bieber reckons William should take Propecia to combat his thinning hair. These photos suggest it might take more than thatTom Sykes08.08.12 11:04 AM ETAnwar Hussein Collection / ROTA / Getty Images ; Indigo ; Getty Images ; WPA Pool / Getty ImagesWilliam's Bald Spot Throught The AgesJustin Bieber recently joked about Prince William's noticeably thinning head of hair to UK's Rollercoaster magazine, telling the Duke of Cambridge he should get pills for his failing follicles. "I mean, there are things to prevent that nowadays, like Propecia," the 18-year-old pop star told the magazine. "I don't know why he doesn't just get those things, those products. You just take Propecia and your hair grows back. Have you not got it over here?" Easy for the luxuriantly-coiffed Bieber to say. Carl De Souza / Getty ImagesFull HeadedYou have to go back to 2004, when William was 22, to find a head of hair of which Bieber would approve. I know - doesn't Harry look adorable? Anwar Hussein Collection / Getty ImagesIt's All RelativeIn 2006, Prince William gets a taste of what lies in store as he greets his Uncle, Prince Edward, Earl of Wessex (while his brother Prince Harry greets Prince Andrew, Duke of York) as they attend the Service of Thanksgiving at St. Paul's cathedral to mark the Queen's 80th Birthday and Prince Phillips 85th birthday Tim Graham Picture Library / Getty ImagesOn The Head, Son!2006: The first hints of trouble ahead, as Prince William signs the golden book of Frankfurt at the Waldstadion aged 23Valery Hache, AFP / Getty ImagesView From The Top Prince William exposes his head to view in 2006 Anwar Hussein Collection / ROTA / Getty ImagesThinning OutBy 2008, as William, aged 25, attends the under 18s water polo championship the bald spot is starting to emerge with increasing clarity. Anwar Hussein / Wire Image / Getty ImagesHairless HeirIn this photo taken in 2009, Prince Willliam walks with a group of homeless young people helped by charity Centrepoint. You can see the bald spot is starting to make its presence felt. But its nothing compared to the guy on his right. WPA PoolEven Less Hair ApparrentA close-up from the same trip. Indigo / Getty ImagesBaldly Bow 2011: Prince William bows to his grandmother Queen Elizabeth II after showing her around a Sea King search and rescue chopper, and reveals his 'sea of tranquility.' Clive MasonThe Champion2012: These days, William knows how to work the look - shades, close cropped hair and make sure all photos are taken from below. Sweet. Here, he attends the fourth round tennis match between Andy Murray of Great Britain and Richard Gasquet. Chris Jackson / Getty ImagesEndgameIt could be worse. You could be George Costanza, sorry, Prince Albert II of Monaco.