AGE VARIATIONS IN SIBLING CORRELATIONS FOR HEIGHT, SITTING HEIGHT ANDWEIGHT

Familial correlations for height, silting height and weight have been studied in a sample of 1278 siblings for the Biscay province (Basque C ountry), aged 4+ to 24+ years. The data have been internally standardi zed according to sex and age of the individuals. The degree of resembl ance among sibling has been expressed by intraclass correlation coeffi cients. The total sample has been divided into three age categories: < 12 years, 12-15 years, and greater than or equal to 15 years, in orde r to examine the effect of age on sibling correlations. In general, ch anges with age have been observed: sibling correlations for height sho w a clear upward trend through the considered growth period, reaching a value of 0.48 from 15 years of age. Intra-correlations for weight sh ow a slight downward trend with age. Sitting height shows a rather low correlation before 12 years of age, but equally high values in the ot her two ranges of age (0.48 and 0.47, respectively). This study confir ms that the sibling resemblance for the analysed traits fluctuated thr ough the growth period-height and sitting height showing similar patte rns of variation with age-and that, after puberty, the degree of genet ic determination is higher for bone measurements than for weight.