Idonea was born in 1170 to a wealthy landowner in the flourishing village of Herste (which later became known as Herstmonceux) in Sussex. Her mother died when she was young and her father never remarried, leaving her the only heir to the estate and lands, which made her a good catch in marriage. She married in the summer of 1188 to Ingelram de Monceux, a descendant of Drogo de Monceux who hailed from Monceaux (note the different spelling), in Bayeux, Normandy.
A year later was blessed with a son, Waleran. In 1195 Ingelram went crusading with his King, leaving Idonea in charge of a large household and estate. She had her own seal to seal documents with and it showed her in a long dress with long, trailing sleeves holding a spindle in one hand and a bird, probably a hawk, in the other.
She was a great patroness of the arts and the church. With her husband away she indulged herself and learned to shoot the long bow, mostly as a hobby. Also, with the country in a state of turmoil and the risk of raids along the coast by French pirates she could help defend her home if necessary.
