Analysis of GP records of 642 eight-year-old children alongside the childhood records of their parents has ruled out the basis of the hygiene hypothesis.
This states that reduced exposure to early life infections and antibiotic treatment in childhood is detrimental to the immune system, increasing the risk of atopy.
But the latest study demonstrated that 97 per cent of the children had at least three infections by the age of five, compared with 69 per cent of their parents.
Antibiotic use before the age of five was also higher among the children, with 98 per cent having a record of an antibiotic scrip compared with 76 per cent of their parents.
The children had been followed up annually since birth. By the age of eight 19 per cent had atopy, 13 per cent suffered from wheeze and 21 per cent had seasonal rhinitis.
When parental atopy and birth order were considered, no association was found between infection counts and atopy, with an odds ratio of 1.01 per infection. Positive associations were found for wheeze and seasonal rhinitis, with the risk of current wheeze increasing by 7 per cent for each antibiotic scrip.