Fulk was the son of Geoffrey I, Count of Anjou and Adele of Meaux. He was born about 970. Fulk was born into a of counts going back nearly a hundred years. His father, grandfather, great-grandfather and second great-grandfather had all been counts of Anjou before him. His father, Geoffrey I had been preparing Fulk to be count as he raised him. He was about age seventeen when his father died and Fulk became the next count. Two years earlier, in 985, his father arranged for him to be married to Elizabeth de Vendome, daughter of Bouchard, Count of Vendome. His nickname "Nerra" meant 'the Black'. It was probably given to him after his death.