Sylvie Vartan and David Hallyday have their birthdays which fall one day apart. She (80 years old) was born on August 15, 1944 while her son (58 years old) was born on August 14, 1966.
The anniversary was a priori celebrated a few days late since Sylvie Vartan published this short video Thursday August 22. We see there Cameron, the son of David accompanied by his wife Alexandra Pastor, carry the very large common cake. Sylvie et David blew out the candles together in front of an assembly made up of family members and close friends.