Although genes will often be shared within a family, most specific items of genetic information will have been generated by examining or testing an individual. Such information will, inevitably, belong more strongly to that person than to his or her relatives. To claim that the information belongs to the family is to miss the point. In current practice, to make that claim asks the question that the test would usually be setting out to answer: is mutation M that is found in person P also present in relative, R? If it is present in R, then P and R share the particular genetic variant; otherwise they do not.

There are occasions when genetic information does belong intrinsically to the family. For example, in a genetic linkage study looking at the pattern of sharing of DNA sequences among family members, the results are meaningful only when the family is …