The male gamete fertilizes a female gamete.

And the job of sex went to a special cell called the gamete.

Normally a gamete (sperm or egg) carries a full set of chromosomes that includes a single copy of each chromosome, as aneuploidy generally leads to severe genetic disease in the offspring.

Well, the mom always donates an X chromosome, so in no way does what the haploid genetic makeup of the mom's eggs, of the gamete from the female, in no way does that determine the gender of the offspring.