A child whose parents are so addicted to drugs they end up unsupervised, undisciplined, and otherwised neglected and forced to fend for him or herself and/or younger siblings at too early an age. These so-called parents, who never should have had kids, often leave their kids home alone while they stay in their rooms either high, coming down from a high, or go out looking for their next fix, and often don't care about their children unless child welfare intervenes. A few lucky drug orphans will have a babysitter or nanny who truly loves and cares for the child, but quits due to the sheer mental and emotional exhaustion of dealing with the drug-addicted parent(s).
Drug orphans younger than 5 are often found without clean diapers, are not toilet trained, and enough food or drink to live on. School-aged kids show no interest in school and are often absent, primarily due to the emotionally absent parent's indifference to his or her child's education, and sometimes due to the oldest kid's having to care for her younger siblings (mostly affecting girls).
Preteen or teen drug orphans show rebellious behavior, sometimes acting out in the exact same way their addicted parents do while at the same time raging at them for neglecting them. The parents are to blame for setting such a bad example. Other teen drug orphans will rebel by doing the exact opposite of what their parents have done: they live squeaky-clean; honor students, drug-free, alcohol-free, etc. These kids do not want to repeat their parents' mistakes, so they go to the opposite extreme. They're the ones with the character to rise above their poor or nonexistent upbringing to be somebody.
No wonder those kids running the streets are so wild: their mom has a crack habit and their dad's on meth--they're drug orphans and should have been taken from them years ago and put into foster care until the parents got clean!