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.
On the other hand, if you resort to urine test, they are detectable for a period of 2 - 5 days after the last use. Yet another test is the hair test, wherein opiate drugs are detectable for up to 2 - 3 months from the last use. All in all, everything comes down to your determination at the end of the day.