Scientists unpicking the genetic jigsaw of life have discovered a "Celtic gene" which makes Scots more likely to have Multiple Sclerosis than anywhere else in the world.
The MS bombshell is the latest in a growing line of genetic discoveries that leave us feeling helpless.
But scientists now believe these new genetic hotspots are merely what is left over from ancient immunities that helped us survive.
Medical gene busters are driven by one goal - to cure a raft of genetic illnesses. The quest to unravel the human gene has passed the halfway mark and genetic science now stands at the threshold of explosive discoveries.
For the past eight years teams of scientists from around the world have been trying to identify billions of molecules which decide human genetic make-up.
If you could unravel all the DNA from a solitary human cell you would get a single, microscopically thin thread about five feet long.
On this thread are close to three billion base pairs of molecules, coded A, T, C or G that are the genetic code for who we are and how healthy or sick we are destined to be. Within the thread there are 100,000 important genes that control body functions.
Already there have been important medical milestones. Single gene defects that lead to cystic fibrosis, sickle cell disease and Huntington's chorea have been located.
And by 2003, two years ahead of target, scientists believe they will have the whole sequence mapped and made freely available for medical research.
One molecular genetics specialist said: "We are all condemned by what is, or is not, in our genes. And the aim of the research is to cure the illness."
Scots already owe our lives to this same genetic weakness.
As in the blood illness sickle cell anaemia, a mutation of a former genetic protection against malaria which mainly targets African and Asians, scientists are now certain the problem "Celtic gene" was once the crucial edge that allowed our ancestors to survive a mystery sickness that killed off their genetically inferior neighbours.
Dr Richard Wilson, a molecular biologist at Glasgow University, highlighted three cases where the recent discovery of human genes is linked to old diseases.
Some of these genes may hold the key to modern illnesses such as Aids that pose a global threat to mankind.
He said: "Researchers have found a gene which is most common in Sweden which is resistant to HIV.
"It is believed that this resistance originally stemmed from a genetic protection against the plague that swept across Europe in the Middle Ages.
"This is similar to cystic fibrosis, which typically affects one in 2000 people although nearer 100 more per 1000 may be carriers.
"Prevalent mainly among caucasians in west and central Europe, it is now thought CF might be linked with a resistance to cholera.
"And another gene particularly found in people from Scotland and Ireland offers protection to phenylketonuria, which basically means resistance to the toxins found in rotten and mouldy vegetables. This would have been important to people who had to store their food over the winter."
Dr Wilson says nature is so strongly geared towards human survival that it only takes 1000 years for a gene to claim its place in a population, even though it might only be there to help two per cent of carriers.
Researchers studying why three out of every 100 Scots may develop MS compared to one per 1000 in England, double the rates found elsewhere in Europe, are now on the trail of the ancient mystery illness it protected us against.
It could have been a flu virus thousands of years ago has left true Scots, with a Mac or a Mc surname, with a rogue HLA-DR2 gene and now 24 per cent more likely to get the crippling disease. Why this particular building block of life is more prevalent in Scots is unknown. …