HEIDELBERG, GERMANY - JULY 20: Catherine, Duchess of Cambridge looks into a microscope as Prince William, Duke of Cambridge and Baden-Wurttemberg's Minister President Winfried Kretschmann (Alliance '90/Greens) look on during a visit to the German Cancer Research Institute on day 2 of their official visit to Germany on July 20, 2017 in Heidelberg, Germany. (Photo by Dominic Lipinski - Pool/Getty Images)