The ratio of X- and Y-bearing sperm in ejaculates of men with three or more children of the same sex

Abstract

Purpose: The present study evaluated the proportions of X-bearing and Y- bearing sperm within the semen of donors who were the declared fathers of three or more sons or daughters. Methods: The proportions of sperm were determined using dual-color fluorescence in situ hybridization to identify the X and Y chromosomes. Results: The only difference observed was in semen volume. There was no increase in the proportion of Y-bearing sperm for men with only sons (49.7 ± 1.3%) or of X-bearing sperm for men with only daughters (44.8 ± 2.6%). Conclusions: A preponderance of either sons or daughters in a family cannot be explained simply by an altered ratio of X- bearing and Y-bearing sperm in the father's semen.