Biological factors: This is the very first step that should be taken in order to fully understand why an individual has the tendency to abuse dangerous substances like drugs, harmful potion, alcohol, excessive coffee drinking etc. The first method that could be employed here is called Family Pedigree Model: the family history of the patient is probed so as to detect if any members of his/her family have previously abused the same substances or the others (Corey, 2009). Twin Method is the second technique that would be used to investigate the substance-seeking habit in the patient due to powerful effects of genes and environment. This method is based on the assumption that a set of twins has shared similar genes that could naturally make them behave the same way. even to the point of abusing substances together. However, when they are separated and taken to different environments, they acted differently (Hubble et al., 1999). These two models do not describe a situation where an individual does not come from a family of substance abusers, and does not experience a change in environment but still goes ahead to abuse substances. Therefore, the third method—which is Adoption Method—is quite useful in explaining that such an individual may have picked up the substance-abusing nature through adopting the habit from people around him/her (Straussner, 2003). The three methods highlighted above would be useful in carrying out the initial investigation about a patient’s biological connection with substance-abusing behavior.