Cephalic index in Iranian infants

Studies on Iranian adults revealed that their skulls are commonly brachycephalic. The question of current study is that genetic factors have more prominent role for this matter or environmental factors?
All infants who were born during 6 months period (from April 21, 2016) in the Rasht 17th Shahrivar or Alzahra hospitals, included in this descriptive cross sectional study. Cephalic index calculation was done after caliper measurement percentage of maximal head width and maximal head length relation.
There were 162 male (56.4%) and 125 female (43.6%) among a total of 287 infants. Mean of maximal head width and length were 8.461±0.5980 and 10.810±0.6998 cm, respectively. Mean cephalic index was 78.368±5.090, in the mesocephalic range. One hundred fifteen infants (40.1%) have brachycephalic, 103 cases (35.9%) mesocephalic, and 69 infant (24%) dolichocephalic skulls. There was no statistically significant difference among these parameters between boys and girls.
It seems that brachycephaly among adults is because of environmental factors, and genetic factors have minimal or no influence in this matter. Further studies with larger sample size are recommended.