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NETEHRLANDS - APRIL 30: Princess Beatrix with son Prince Willem Alexander sucking his thumb during ceremony for Queen Juliana's 59th birthday on April 30, 1968 in Netherlands. (Photo by Gamma-Keystone via Getty Images)

NETEHRLANDS - APRIL 30: Princess Beatrix with son Prince Willem Alexander sucking his thumb during ceremony for Queen Juliana's 59th birthday on April 30, 1968 in Netherlands. (Photo by Gamma-Keystone via Getty Images)