Trait controlled by the both environment and genetic factor. Usually, multifactorial traits outside of illness result in what we see as continuous characteristics in organisms, especially human organisms such as: height, skin color, and body mass.
I recently took a drug test for a job. I tested positive for opiates in my urine. I do not and have never taken drugs of any sort other than alcohol. I dont take any prescription drugs, how is it possible that this happened. I hade consumed some beer about12 hours before the test.
I do not know of any PM that uses a blood test to monitor their patients for opiates. They either use the urine dip stick test or send it out to a lab. You can read on these boards that many of the patients' Dr. sends out the sample to a lab.