What can cause attention deficit hyperactivity disorder (adhd)?

The exact cause of ADHD is not well known, however, some of the factors, which can lead to the condition. These are as follows:  

1. Genetic factors, as ADHD seems to run in families.  

2. Chemical imbalance taking place in the brain.  

3. Infections, poor nutrition, smoking, substance abuse at the time of pregnancy, and drinking.  

4. The toxins like lead can influence the development of the brain of a child.  

5. A brain disorder or brain injury, that is, destruction to the frontal part of the brain can result in the issues associated with ADHD.  

the child will have heterozygous dominant chromosomes as characters of his father are dominant over the characters of his mother.

the child is heterozygous