Longitudinal growth of infants in families of 'mixed' and 'non-mixed' ethnic origin in Israel

The present study considers the growth and development of infants whose mother and father come from different ethnic groups with infants born in 'nonintermixed' families. A longitudinal study was conducted on 1081 Israeli children. Their early growth in weight, stature and head circumference was measured during the first two years of life. The investigation encompassed samples from Jewish communities originating ('non-mixed' families) from Europe (E), North Africa (A), Middle East (M), Yemen (Y) and 'intermixed' families: E x A, M x A, Y x A, Y x E and Y x M. Principal component (PC) analysis showed that some of the 'hybrid' infants were very close to one or the other 'original' ethnic groups. For example, Y x A and Y x E groups were located near the Y population. The score of the first four extracted PCs for Y x M group was substantially higher, as compared with both 'original' populations. Discriminant analysis showed a significant difference between the Y x M infants and either Y or M groups. On the other hand, E x A and M x A indicated some detrimental effects of the 'intermixing'; their loadings were considerably lower than those of E, M and A groups. However, only a few of the observed differences are statistically significant. Even 2,500 years of isolation between the Jewish groups, and genetic distances of about 0.25, apparently did not induce significant detrimental effects.