Personal DNA sequences will become a routine tool in the diagnosis of diseases within 10 years, according to the father of genetics, James Watson. He said that, as the costs of the sequencing technology tumble, doctors will be able to use the information to plan more effective treatments for conditions including mental illness, cancer, obesity and diabetes.

Professor Watson, who discovered the structure of DNA in 1953 with his Cambridge University colleague Francis Crick, was speaking yesterday at the launch of the Wellcome Collection, a new national museum based in London that will examine the scientific and artistic connections between people and biomedicine.

Using current technology sequencing a single person's DNA takes 20 technicians around nine months. "In five years the hope is that you could reduce that to a week with just two or three people," said Michael Jones, head of the genomics core lab at Imperial College London. "New technologies are trying to eliminate the technicians you need. The idea is you can take someone's DNA and plug it into a machine and the data will come out."

Prof Watson said the advances would allow doctors to use DNA sequences to help with diagnosis and give advice to people with genetic diseases. "If you have a certain change that causes cystic fibrosis and if your son has one copy of it, perhaps wisdom would be that he shouldn't have children until the partner has had gene tests also," said Prof Watson. "You might warn [your children] you have a gene and they can go and sequence them."

There will also be implications for the treatment of cancer. "Ten years from now we'll realise you shouldn't treat a cancer until you've seen what's gone wrong with the DNA." He cited breast cancer as an example. A woman with defective versions of either of the BRCA genes has a risk of developing breast cancer of up to 80%. There is also an increased risk of ovarian cancer. "A woman doesn't test herself for BRCA1 unless there's a history of breast cancer in her family. But when the cost comes down, just sequence yourself."

If a woman was found to have the disease variant of the BRCA gene, she could consider having a hysterectomy after having children so that she was not also at increased risk of ovarian cancer, he said.

Paul Pharaoh, a Cancer Research UK senior fellow at Cambridge University, said that, although prophylactic surgery was an option for women with faulty genes, increased screening would only affect a small number of women because faults in BRCA genes only account for 2% of breast cancers.

Prof Watson said genetics would help tackle mental illness. At his Cold Spring Harbour Laboratory in the US, scientists have started a project to find the genetic root for every mental condition within 10 years.