Genetic and environmental determinants of level of pulmonary function.

Measurements of level of pulmonary function (one second forced expiratory volume (FEV1) and forced expiratory flow between the 25% and 75% volume points (FEF 25-75)) were obtained on members of 404 nuclear families living in East Boston, Massachusetts in 1974. These families were ascertained through a random sample of children aged 5-9 years. Measurements were obtained on family members on three separate occasions during a 5-year period. These data were subjected to the techniques of path analysis to study the relative contributions of heredity and environment to individual levels of pulmonary function. Genetic heritability was found to be consistent through time (41-47%) and was the same for parents and their children. Common familial environmental effects on level of pulmonary function explained 1-4% of the variability in children and 11-28% in adults. Furthermore, we were able to confirm prior epidemiologic analysis of these data which have demonstrated an effect of maternal smoking on the level of pulmonary function in their children.