Is weed actually a gateway drug?

Via NIDA · Science

Short answer: mostly myth, and the nuance is the interesting part. The National Institute on Drug Abuse says that while alcohol, tobacco, and cannabis usually come before other substances, the majority of people who use cannabis do not go on to use harder ones. Animal studies suggest early THC exposure can change how the brain responds to other substances. NIDA also notes that other factors, like a person’s social environment, are just as critical to that risk. So the order is real. The causation is the part nobody has nailed down. Myth or fact?