[Growth, weight and physical proportionality in twins]

The growth, weight and proportionality of twins aged 1-15 years from the South Moravian Region were studied and compared with a control population. The sample of twins was divided in three groups: identical twins, nonidentical like-sexed twins and boys and girls from the unlike-sexed pairs. No reasonable differences between twins A and B were observed, therefore they are not evaluated separately. All the twins were born in years 1973-1987, the total number was 2,226 boys and 2,302 girls. A comparison with a control population revealed a lower mean height as well as weight of identical twins until the age of 15 years. The mean weight of identical twins was lower than that of nonidentical ones. Similar pattern were observed also in height, the statistical significance was found only in boys and only on a 5% level. Twins from unlike-sexed pairs were more like the control population than twins from unidentical like-sexed pairs, however, the differences in height in girls were not statistically significant. The distribution of proportionality values has shown an accumulation near zero--we can conclude that twins are more proportionate than other children of their age (i.e. less obese and less meagre). As expected, the observed intra-pair differences in identical pairs were significantly lower than in nonidentical like-sexed pairs.