Journalist: Scientists took blood samples from two large, diverse groups of volunteers. All the volunteers in one group reported that they enjoyed eating vegetables, whereas all those in the other group disliked vegetables. When the blood samples from the group that disliked vegetables were analyzed, it was discovered that all the volunteers in that group had a gene in common, the XRV2G gene. This strongly suggests that a dislike of vegetables is, at least in some cases, genetically determined.

The journalist’s argument is most vulnerable to criticism on which one of the following grounds?