Final answer:
In human behavior genetics, if a pharmacological agent is known to affect a personality trait, the gene that codes for the target molecule and any genes whose products interact with the drug or with the target molecule are all candidate genes for affecting the personality trait.
Step-by-step explanation:
In human behavior genetics, if a pharmacological agent is known to affect a personality trait, and the molecular target of the drug is known, then the gene that codes for the target molecule and any genes whose products interact with the drug or with the target molecule are all candidate genes for affecting the personality trait.