In the analysis of familial data, the primary aim is to estimate the degree of resemblance between family members. Here we are interested in the special case where one group of family members consists of one individual, as typified in the following mother-sib situation. The degree of mother-sib resemblance is measured by the interclass correlation, and the degree of sib-sib resemblance is measured by the intraclass correlation. We derive the MINQUE estimators of the interclass and the intraclass correlation coefficients, also new three tests are proposed. Based on Egypt' sibship size, a Monte Carlo simulation is used to compare several different estimators of the interclass and intraclass correlation coefficients, also to compare several different tests of hypotheses of the interclass correlation. Nationally representative hemoglobin level among ever marred women aged 15 to 49 and their children under the age of 5 were recently determined in conjunction with the Egypt Demographic and Health Survey 2000 (2000 EDHS). The interclass correlation between mothers and their children of hemoglobin level and the intraclass correlation among children are estimated and tested.