Shyness in children is quite common and there are many causes linked to it:
Genetics: At least some aspects of personality can be decided by a person’s inherited genetic makeup.
Personality: Emotionally sensitive and easily intimidated infants are more likely to grow up to be shy children.
Learned behaviour: Children learn by following their parents lead. If you are shy then your child can learn this behaviour from you.
Family relationships: Parents who are overprotective can teach their child to be afraid of certain situations which can cause shyness
Lack of social interaction: Children who haven’t been exposed to other children and social situations while they are young can find it hard to interact with unfamiliar people.
Being criticised too harshly: Children who are teased or bullied by significant people in their lives (parents, siblings and close family members or friends) may tend towards shyness.
Fear of failure: Children who have been pushed too hard or taught that failure is not an option can have a fear of trying new things in case they won’t be any good.