Experts have warned that the genetic tests, which claim to predict the risk of developing life-threatening diseases, are a waste of money and can frighten healthy people.
The tests, which often cost 500 pounds, are mostly available over the Internet and the market for them is expanding.
AdvertisementThey claim to calculate the risk of contracting diseases including Alzheimer's, cancer and diabetes.
These tests have featured on television programmes in which celebrities undergo genetic testing to discover their risk of potentially fatal diseases.
However, according to scientists, the wrong genes are often tested, which makes the results almost meaningless.
The Human Genetics Commission, a British Government advisory body, has said that it will call for tighter regulation of the tests, including rules that the claims must be independently evaluated before they can be sold to the public.
Christine Patch, a genetics counsellor at Guy's and St Thomas' Hospital in London and a member of the Human Genetics Commission, said the tests were misleading and preyed on the 'worried well'.
"You are wasting your money. The risk is of the anxiety being caused and also the risk of a false reassurance and the subsequent testing requests to the NHS," the Telegraph quoted her, as saying.
Prof Shirley Hodgson, of the clinical genetics department at St George's, University of London, said the information given out by companies often simply stated that someone was at increased risk of a disease and told them to eat a healthier diet, stop smoking and exercise more.
The experts also said people may be given false reassurance if they were told that they had a reduced risk of developing a disease.
Stuart Hogarth, from Nottingham University, said a strong family history of a certain cancer or heart disease was a better predictor of an individual's risk than genetic tests.
"We are in danger of losing public confidence in what is a exciting area of science," he said.