Heroin is strongly associated with sudden, gruesome, preventable death. It is also extremely addictive, with addicts spending thousands of dollars per day and willing to risk their own and other people's well being to get on. Heroin distribution networks have some of the most predatory and unconscionable sociopaths ever to take human form operating them (basically, the most ruthless dealers rise to the top). That is the way it has always been, from when heroin was first derived from morphine, to the present day. That is how it has been when heroin was legal (including the distribution - cv the opium wars). It is the most physically harmful and addictive drug known. Only alcohol does more harmful to the people it addicts and the people who live with them, and only because it is far more widely used than heroin.
Estelle did marijuana - a drug that mainly causes people to imagine they are creative and insightful when they are thick witted and hungry, has no recorded cases of death through overdose or through habitual use, costs at least twenty times less than heroin, is less addictive than Coca Cola, and can be obtained as easily (and in Amsterdam, as legally) from sources not more sinister (Admittedly the distributors of cannabis have not as up front about their ties to armed groups as Coca Cola has been with its marketing itself through the US army, but there are many more and much stronger evidence of direct links between heroin distribution and war-lordism, arms trading and terrorism: look at Vietnam in the 60's, Myanmar and Laos in the 80's, Afghanistan in modern times. A drug that is smelly, bulky, low priced, and as easy for most users to leave as to take, a drug that most users would not knowingly risk their lives to take, is never going to have the profit margins of heroin.)
Another point: Why would somebody who grew up in an environment where taking drugs was normal adult behaviour, think taking drugs was normal adult behavior?
There is some dispute about the role of genes and environment, but there is evidence that the children of heavy alcohol drinkers, nicotine smokers, coffee drinkers, and heroin addicts, are more likely to use their parents drug of choice as adults, than the children of parents who don't use those drugs.
So maybe Estelle's father was a pot-smoker and not a heroin addict at all.