Genetics
This is something experts have been investigating and debating for years, but the answer is slowly emerging at last. We now know that genetics play a large part – if your parents have an allergy, such as hay fever, you’re more likely to suffer from it too. For example, a child in the UK has a one in five chance of having an allergy – this chance doubles if their parent has one and this chance increases to 60 to 80% if both parents have one.
Contact with animals
A study from the University of Michigan discovered that Cat & Dog owners are less likely to suffer from pet allergies than non-pet-owners if they lived with them during the first year of their life, because daily exposure to animals may strengthen your immune system. The scientists found that children who grow up with dogs are at a particularly low risk of developing allergies.

Hygiene Hypothesis
The immune system needs to come into contact with micro-organisms and bacteria whilst it is developing at infant stage then responds appropriately later in life.
Now most of us live in a cleaner environment than ever, it could be argued the inadequate exposure to allergens is resulting in tendency to allergy.
Diet
Some experts also point to a change in diet and have questioned whether lower levels of vitamin D and omega-3 fatty acids might cause an increase in allergies. A study from scientists at Aberdeen Royal Infirmary found that there could potentially be links between a diet rich in vitamin E during pregnancy and the likelihood of the baby suffering from allergies when they're older. Good sources of vitamin E include dark green vegetables such as broccoli and spinach, and almonds.
Pollution

Air pollution could have an effect on allergy suffering. There's evidence that the pollutants also stimulate pollen production.
Do you think you may have an allergy? Find out more about allergy symptoms by clicking here.

