title: The ratio of X- and Y-bearing sperm in ejaculates of men with three or more children of the same sex.
abstract: OBJECTIVE
  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.
authors.affiliation: Centre for Human Genetics, Edith Cowan University, Joondalup, Western Australia.
authors.forename: J
authors.initials: J
authors.lastname: Irving
authors.forename: A
authors.initials: A
authors.lastname: Bittles
authors.forename: J
authors.initials: J
authors.lastname: Peverall
authors.forename: A
authors.initials: A
authors.lastname: Murch
authors.forename: P
authors.initials: P
authors.lastname: Matson
mesh_terms: D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D012661:Semen / Q000166:cytology*; D019849:Sex Determination Processes; D017678:Sex Distribution; D013094:Spermatozoa / Q000648:ultrastructure*; D014960:X Chromosome; D014998:Y Chromosome