Biological factors: Biological factors influence all aspects of our behaviour. A wide range of biological factors such faulty genes, endocrine imbalances, malnutrotion, injuries and other conditions may interfere with normal development and functioning of the human body. These factors may be potebtial causes of abnormal behaviour. According to the Biologiacal model, abnormal behaviour has a biochemical or physiological basic. Biologists have found all the abnormal behaviour is the result of problems in transmission of massages from one neuron to the other. A thin space called synapse separates on neuron from the next, the massage must move across that space, when an electrical impulse reaches a neuron's ending, the nerve ending is stimulated to release a chemical, called a neurotransmitter. Anxiety disorders have been linked to low activity of the neurotransmitter gamma aminobutyric acid (GABA), schixophrenia to excess activity of dopanine and depression to low activity of serotonin.