ABSTRACT
Background: Aggression has been hypothesised with biological instinctual theory, frustration theory and social learning theory. The biological instinctual theory was based on hereditary factors and is associated with XYY syndrome. Objectives: To find out the presence of extra Y chromosome in aggressive taller males of north Indian region. Materials and Methods: Buss and Perry questionnaire was used to find out the aggression of the subjects. The height was measured with the help of metallic tape. Quinacrine dihydrochloride and Macllvaines Buffer was used to stain the buccal smear slide for the general screening of the number of Y chromosomes. The conventional metaphase was prepared for the confirmation of number of Y chromosomes and the slides were stained with giemsa. Observations: The aggression was found more in taller males and they had no extra Y chromosome. Conclusions: Extra Y chromosome may be the cause of aggression and more height in males. But in the present study of males of north Indian region no extra Y chromosome was found in aggressive and taller males.