Introduction:
Biological growth of children is genetically determined but there are a lot of factors modifying trends of growth. Among them the most important seems to be parents’ education and number of children in family – socio-economical factors. Factors don’t affect orga-nism individually. Interactions between them can increase or decrease. So the aim of the work was to estimate the influence of socio-economic factors like parents’ education and number of children in family on coordinational traits of children aged 10–11.

Material and Methods:
199 children aged 10-11 underwent medical examination in 2008 in Polkowice and data collected were used in this study.. Information on parents’ education and number of children was used to divide children into four groups: lower education and 3 or more children in family, lower education and less than 3 children in family, higher education and more than 3 children in family and higher education and less than 3 children in family. Three coordinational traits were measured: short time memory, precision of hand and speed movement of the hand. MANOVA test was used to estimate differences between groups and to check interactions between factors.

Results:
From among 4 groups of boys, these from the worst socio-economic status of family received the worst results in all three tests. Differences between them and the rest of the groups were statistically significant. Differences between the rest of the groups were not statistically significant. In the girls groups children from families with higher parents’ education received statistically significant better results in test of memory. There were not differences between all 4 groups in precision of the hand test. Girls from family with higher parents’ education and 3 or more children in family received the best results in speed of the hand test.

Conclusions:
Boys are the gender more eco-sensitive. The family with more than 2 children in family and with ower parents’ education don’t ensure proper conditions of the coordinational development. Among girls parents’ education seems to be more important factor than number of children in family for development of the short time memory. Both factors didn’t affect precision of the hand. The best conditions of hand‘s speed development seems to be in family with lot of children, but only if parents are better educated.