Ethnic and secular influences on the size and maturity of seven year old children living in Guatemala City.

Three groups of children, those of European parentage, those of Guatemalan parentage, and those of mixed European-Guatemalan parentage were measured for height, weight, and skeletal maturity. The children were born between 1945 and 1965, they were all of high socioeconomic status, and they all attended the same private school in Guatemala City. At 7 years, the boys of the European group were significantly taller than boys of the Guatemalan group. European and mixed European-Guatemalan girls were significantly taller than Guatemalan girls. These results are maturity independent. The influence of skeletal age was removed statistically by analysis of covariance. Girls of the mixed group were significantly heavier than girls of European and Guatemalan groups. Mixed group girls also had more significantly advanced skeletal ages than European girls. When the patterns of size and maturity status are analyzed by sex, there is evidence for a relatively greater environmental influence on the boys and a relatively greater genetic influence on the girls. Dividing the data into two birth year cohorts, 1945 to 1955, and 1956 to 1965, does not provide evidence for secular trends in growth or maturation. These results are similar to those from studies in developed nations that report an end to the secular trend for the "well off" population of those countries.