Marianne moved in with Pontecorvo at the "Hôtel des Grands Hommes" on the "Place du Panthéon" on 4 January 1938. Their son, Gil, was born on 30 July. Her visa expired, and she had to return to Sweden in September. Pontecorvo accompanied her, leaving Gil behind in a residential nursery in Paris. Travelling back to Paris alone, he dined with Manne Siegbahn and met with Niels Bohr and Lisa Meitner on 12 October 1938. Pontecorvo was now unable to return to Italy because of the Fascist regime's racial laws against the Jews. This caused the breakup of the Via Panisperna boys, with Fermi moving to the United States. Pontecorvo's family also dispersed. Guido moved to Britain in 1938, followed by Giovanni, Laura and Anna in 1939, while Gillo joined Pontecorvo in Paris.