Millions of men in the UK suffer problems in the bedroom due to ageing, obesity and illnesses like diabetes.
But now scientists have discovered there could be another surprising reason why so many struggle to perform: their blood type.
A new study shows men with blood types A, B or AB are up to four times more likely to suffer impotence, or erectile dysfunction, than men who have blood type O, according to the Daily Mail.
The findings are potentially significant as it's estimated more than half of all men carry A, B or AB blood.
Roughly 44 per cent have type O.
Scientists who made the discovery say it supports earlier research showing blood type also influences the risk of developing heart disease.
One in 10 men suffers erectile dysfunction at some point in their lives.
Some studies suggest more than a third of those over 40 are affected.
Although drugs like Viagra have revolutionised treatment, around 30 per cent of men who take those drugs see no improvement.
Until now, doctors thought lifestyle-related factors such as smoking, being overweight and having high blood pressure were the key triggers.
But the latest study, by a team at Ordu University in Turkey, suggests many may be at risk of erection problems simply because of the blood type they were born with.
Researchers recruited 350 men in their 60s and split them into two groups according to whether they suffered problems getting or maintaining erections.
Each man gave a blood sample.
The results, in the Archives of Italian Urology and Andrology, revealed men with types A, B or AB were three to four times more likely to flop in the bedroom than those with blood type O.
Just 16 per cent of O blood types had problems getting aroused, compared to 42 per cent of A types.
Even when researchers accounted for whether the men smoked, or had high blood pressure, the differences were still substantial.
It's unclear how blood type might affect sexual performance but the theory that it can influence health first emerged nearly 100 years ago.
Since then, studies have claimed it determines the risk of numerous conditions, including heart disease, cancer, infertility and stomach ulcers.
Heart problems, for example, are much less likely to be found in men with O-type blood than other groups.
One theory is people with type O have a lower genetic risk of some illnesses.
Research suggests, for example, that they are less likely to have dangerously high cholesterol levels that harm blood flow to both the genitals and the heart.
In a report on their findings researchers said: "In our study, A, B and AB blood groups were related to the risk of erectile dysfunction.
"We believe this study is very important. It's the first to show such a relationship."
Dr David Goldmeier, sexual medicine expert at Imperial College London, said men with blood types A, B or AB should take extra care of their health in order to ensure healthy hearts and sex lives.
"They need to be more assiduous about getting the right amount of exercise and eating healthily," he said.