Kidston is related to nobility. Her uncle is Charles Allsop, the 6th Baron Hindlip. He used to be chairman of Christie's. His daughters are The Honourable Kirstie Allsopp and The Hon. Sofie Allsopp. They work as television presenters. They are Kidston's cousins. Both of her parents died of cancer. Kidston had breast cancer when she was 37 and has since recovered. Kidston's partner is record producer Hugh Padgham. They met when she worked as his decorator. They have a home beside the Thames in West London and another home in Gloucestershire. She has a step-daughter. She is dyslexic.