The study observed population of 484 generation restrictive genealogies col
lected in four Croatian regions during 1970/71 within "The study of fat and
carbohydrate metabobism indicators correlated with the occurrence of diabe
tes in animal fat and oil consuming population groups". The genealogies wer
e collected on two islands (Brac and Hvar) and in two continental regions (
Sinjska Krajina and Srijem). Genealogy Structure Index (GSI) was defined as
quantitative indicator of genealogy structure. GSI was continuos variable
which, by its extreme, describes vertical and horizontal type of genealogy
structure, independently of the way genealogies were collected. Genealogy s
tructure of surveyed population was described on the basis of participation
of different genealogy types. Populations of the island Hvar and Brac show
ed to have horizontal genealogy type, continental population of Sinjsha Kra
jina showed to have mixed type and continental population of Srijem showed
to have vertical type of genealogy structure.