Gerrit Speijer was a son of Levie Speijer and Jansje Berclau. He married 10 April 1918 in Amsterdam to Sara Suesan, daughter of Juda Suesan and Vrouwtje Berclou.
He had three other sisters: Elisabeth, Sara en Grietje.
City Archive of Amsterdam, archive card of Levie Speijer and website www.wiewaswie.nl.