Fathers exposed to radiation pass on the damage to their children, research suggests.
Fathers may pass on mutations
Offspring of radiation-exposed male mice had mutations in their cells suggestive of radiation damage, despite having had no direct exposure.
The Leicester University team said studies of Chernobyl victims indicate the same is true in humans.
They presented their findings at a conference held by the Children with Leukaemia charity in London.
Leukaemia is the term used to describe a number of cancers of the blood cells.
Radiation is recognised as a risk factor for this cancer in children who are directly exposed to it.
Radiation damages the genetic material of cells.
Now scientists have compelling evidence that the damaging effects could be passed down the generations.
By studying mice, Professor Yuri Dubrova and colleagues found fathers who had been exposed to radiation passed on genetic mistakes to their offspring.
The baby mice had mutations in their sperm and eggs similar to those of their "exposed" fathers.
When these mice grew up and had offspring of their own they passed on the faulty genes through their damaged sperm and eggs.
Professor Dubrova said: "Our results show that radiation-induced instability can be transmitted for at least two generations."
The team then looked at examples where humans had been exposed to radiation.
Fathers who lived in Ukraine and Belarus - areas that were heavily contaminated by fallout from Chernobyl - had mutations in their sperm.
Mothers from the same areas had normal eggs, however.
Professor Dubrova said it remained to be seen whether human fathers might pass on these mutations to their children.
Ken Campbell from the Leukaemia Research Fund said the findings were "plausible" but he did not think that this inheritance of genetic damage would cause leukaemia in humans.
"There have been a large number of studies done in countries around the world on children of fathers with above average radiation.
"None suggest that this is a factor in childhood leukaemia. In fact, there is strong epidemiological evidence to suggest this is not a factor in childhood leukaemia.
"Fathers being irradiated does not increase the risk of their children developing leukaemia," he said.