Johnny often hits his brother even though his brother does not do anything to antagonize him. Johnny's aggression is most likely due to a combination of

His aggression is a combination of his genetic makeup, the environment he grew up in, and the fact that aggression can be evolutionarily adaptive

Explanation:

In psychology, aggression refers to different types of behaviors that can re lead to physical & psychological harm to either the individual exhibiting the aggression, others people or even objects in his/her immediate environment.

Factors that could lead to it could be biological factors such as his genetic make like if he is a man or woman; environmental factors like the home and environment in which he/she grew up; physical factors like family history.

In summary, his aggression is most likely due to a combination of his genetic make up, the environment in which he grew up and the fact that his aggression could have been evolutionary.

it takes about 30 days for it to break down

conduction, convection, radiation