Egg and sperm donors should consider waiving their anonymity because it can no longer be guaranteed, according to the UK fertility regulator, the Human Fertilisation and Embryology Authority (HFEA).

Prior to 2005 donors could be anonymous, but donor conceived children have been increasingly finding their biological parents through ancestry websites.

The HFEA said it had seen a 200% rise in the number of people requesting information on their biological parents since 2010. It has made it possible for donors to voluntarily remove their anonymity from its register and has changed the advice it provides to clinics, asking them to highlight the popularity of DNA websites.

Sally Cheshire, chair of the HFEA, said: “The recent rise in the number of people using DNA testing websites to trace their ancestry means that more people may inadvertently find out that they were conceived through a donor.

“We are talking to these companies about making sure they provide clear information on their websites about the potential risks of using their DNA matching services and that they signpost their users to appropriate support.”

Three million people had used home DNA kits by 2016, but the total now was thought to be about 30 million. Around 100 million people will have used one by 2021, according to the fertility charity the Progress Educational Trust, which has called for support systems to be set up for anyone affected by the rise in home DNA testing