Published in The American Biology Teacher, Volume 73, Issue 4, April 1, 2011, pages 213-216.
The definitive version is available at https://doi.org/10.1525/abt.2011.73.4.5.
We question the use of mechanical models, such as coin flipping, to represent the probabilities of gender distributions in sibship families consisting of two children. Both the assumptions of the models and the reliability of the data should be evaluated. Using models without these critical evaluations may tend to perpetuate myths rather than elucidate biological realities.