A family set method for estimating heredity and stress: II. Preliminary results of the genetic methodology in a pilot study of negro blood pressure

THE PURPOSES of this report are to describe a method to evaluate genetic components of variability using survey techniques, and to present preliminary results from the application of this method to crude measures of skin color and height, and to blood pressure. Most recent evidence suggests that the genetic contribution to the observed variability between individuals in blood pressure, systolic and diastolic, is multi-factorial in nature, and that hypertension is merely “one tail ” of a continuous distri-bution [I, 21. While this point of view does not as yet have universal acceptance, meaningful estimates of the genetic contribution must ultimately relate differences in blood pressure to quantifiable genotypic differences irrespective of the number of genes involved or the nature of their action. Fortunately, genetic theory specifies the proportion of independently segregating autosomal genes which various biological relatives will share on the average. Thus, parent and offspring or siblings will share half of their genes in common; fist cousins, one-eighth, and so forth. These pro-portions may also be interpreted as the probability for any given (autosomal) gene specified in one person that the stated relative will possess the same gene, in the sens