Animals have defence mechanisms and a general rule is if they have teeth they bite. Hedgehog personalities and our reactions can be major factors in biting. Hand reared hedgehogs are known to be common biters as well as those hand fed treats such as mealworms.
A nervous or dominant hog will bite more often than confident and calm hedgehogs. If the person holding them is nervous it may show and result in being bitten. Hormones and quilling also play factors in biting.
To inhibit biting be sure you have clean unscented hands (no food or perfume) and know that if bitten it stings but the shock is worse than the incident.
If bitten some hogs clamp or repeatedly bite. Blowing on their face often releases and allows you to regain control. It is crucial to remain calm and continue handling after being bitten. Hedgehogs will repeat buying if it rewards them back into solitude.
Often people are bitten during anointing. This behaviour is when a hedgehog finds a new or unusual scent. They lick building saliva to a froth. To gain more of the taste, after licking repeatedly the hog will bite. This often shocks new owners or handlers.
Biting is natural and can be painful. It us not personal and can be dealt with calmly. Some hogs bite more than others, and even a relaxed hog can bite without warning. If bitten the area should be washed, the hog should continue to be handled to rebuild the bond and ignore the unwanted behaviour. Exotic animals have unusual behaviour.