>On Aug 12, 2:43 pm, ta nc.rr.com> wrote:

>> The sex of a human is determined by the male sperm (only the male has
>> the region on the Y chromosome, the SRY gene I think, that can produce
>> a male). But presumably every embryo has an equal chance of becoming a
>> male as it does a female.
>>
>> So what determines whether that SRY gene is activated and the embryo
>> becomes a male, or whether it becomes a female?
>>
>> I imagine many will simply say it is random . . . which is another way
>> of saying "I don't know". :-)

>
>I was just reading about that today but don't know how to think about
>this material yet.

>Far from being random chance, there are a large number of factors that
>appear to influence, even if only very slightly, whether a couple will
>have a son or a daughter. The generalized Trivers-Willard hypothesis
>can explain the evolutionary reasons why these factors affect the sex
>of the child. Evolution helps parents pass on their genes in the most
>efficient way possible.