A cardiac researcher is trying to determine if a pattern of very high blood cholesterol is genetic in a group of Pennsylvania Dutch. Therefore, the scientist looks through years of medical records, plus patterns of marriage through several generations. The investigator is doing a type of hereditary research called .

Pedigree analysis

Explanation:

Pedigree analysis is a type of research used to study gene inheritance in humans. It is used to interpret genetic information or trait patterns displayed in a family tree. Pedigree analysis tries to analyze and determine the absence or the presence of a trait in relation to family members.

When a pedigree is done it  shows the family history of a trait, hence can reveal, what chromosome the trait is linked to, family genotypes, dominant or recessive traits and phenotype probabilities in unborn children.

Therefore, from the question, the investigator is doing a type of hereditary research called pedigree analysis.