Abstract. Variability in stature among young children is often ascribed to health and nutrition differences in malnourished populations and to genetic differences in well‐nourished populations. Hence, it was hypothesized that parent‐child correlations in malnourished Guatemalan populations would be markedly lower than those reported for European samples. Instead, it was found that parent‐child and sibling correlations were similar in both kinds of populations. The simplest interpretation of these results is that variability in stature among malnourished children is as much a reflection of genetic differences as in developed nations. However, explanations can also be advanced which would attribute the higher than expected correlations to the environment. For instance, it could be that socioeconomic and nutritional status is correlated across generations. In other words, parents who had relatively better conditions as children are more likely to provide a better environment for their children. Consequently, the relative contribution of genetics and environment to variability in height is still unsettled. Nonetheless, it appears that variability in body size in malnourished populations, regardless of the relative importance of its causes, is a useful indicator of health and nutrition. Copyright © 1977, Wiley Blackwell. All rights reserved