Children are twice as likely to develop allergic diseases including asthma if a parent of the same sex is a sufferer, new research suggests.
Professor Hasan Arshad, a consultant in allergy and immunology at Southampton General Hospital, found that allergies such as asthma and eczema were gender-related and not simply hereditary.
"We have known for decades that allergy runs in the family and many thought that maternal effect was greater than paternal effect due to a mother's closeness to her child, but we have discovered the inheritance is from mother to daughter and father to son," Professor Arshad said.
His team assessed 1,456 patients recruited from birth 23 years ago and found the risk of asthma in boys was only increased if their fathers suffered from the condition while, if mothers had asthma, it doubled the risk in their daughters but not sons.
The research, published in the Journal of Allergy and Clinical Immunology and funded by the National Institute of Health in the US, also showed maternal eczema led to a 50 per cent increased risk of eczema in girls, while paternal eczema did the same for boys.
Professor Arshad, who is also chair of allergy and immunology at the University of Southampton, said: "With these groundbreaking findings, we should see a change in the way we assess a child's risk of disease, asking girls for the allergy history of their mother and boys for that of their father.
"This work also opens up novel areas for further research in the genetics of allergy as to why this sex-dependent effect occurs and, if we can find the reason, we can try to find a way of preventing sex-specific disease."