The sex ratio of Japanese twins.
I have previously suggested that the sex ratios of multiple births registered in Japan are biased. Data published by Imaizumi[1982a, b] are consistent with the suggestion that this alleged bias diminished during the two decades preceding 1974. If true, this would provide additional evidence for my claim that the sex ratio of monozygotic twins is low.
D005260:Female; D005826:Genetics, Medical; D006801:Humans; D007564:Japan; D008297:Male; D011247:Pregnancy; D012744:Sex Ratio; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic