[1] He was born near Tralee, one of the seven children of the Reverend John Day of Lohercannon, County Kerry, Chancellor of Ardfert.
His paternal grandfather, also named Edward, had been a prosperous merchant, who married Ellen Quarry of Cork city.
His mother's family were a branch of the FitzGerald dynasty, and had held the title Knight of Kerry for centuries.
[6] They had six children, including the Reverend Edward Day, who succeeded his father as Rector of Kiltallagh but outlived him by less than a year, Robert Day, who was High Sheriff of Kerry in 1808, and Lucy who married the Reverend William Godfrey, Rector of Kenmare.
Robert was deeply affected by Edward's death, mourning him as a man of "fine parts and great erudition and of benevolence unbounded".