Psychology researcher Elizabeth Loftus explains how easy it is to implant false memories in unwitting subjects:
We gather a whole bunch of data from you, about your personality, thoughts about different foods, all kinds of things. Later, we hand you this computerized profile, which reveals certain things that probably happened when you were a child. In the middle of the list is, say, that you got sick eating strawberry ice cream. We give you false feedback about your data, and then encourage you to elaborate and imagine. Later we ascertain whether you have a belief that it happened to you. Then we offer you a choice from all these different foods. In that example we found that participants didn’t want strawberry ice cream as much. … We did a similar kind of false-feedback study with vodka. If we make people believe that before the age of 16 they got sick drinking vodka, they don’t want to drink as much vodka.
See another Loftus test demonstrated above.