female:male ratio in K-3 kids

[joyce maxwell]

On 11 Jan 1996, Terry McTigue wrote:

> 
> Since sex is determined by the father's contribution to the genetic
> material, what could be the mechanism linking the sex ratio to the
> mother's age?
> 
The question of sex ratio was one of the topics on my Ph.D. qualifying 
exam nearly thirty years ago, and at that time, it was theorized that 
repeated exposure to Y-bearing sperm stimulated an immune response, so 
that older women were more likely to react against them.  This hypothesis 
seemed to be supported by the increase in male births at wartime, when 
couples tended to marry young and conceive shortly thereafter.  I do not 
know whether this theory has been subjected to experiment.
Joyce Maxwell