As much as I know, process of spematogenesis is producing male and female sperm thru the process of spermatogenesis via splitting of the parent cell to two. So, the ratio is allways close to 50/50. FISH analisis confirmed this very many times.
I know that there is a clinic in CA (Fertility institutes; doctors Steinberg and Peck) offering this kind of test. They claim that sperm can contain disproportional amount of female and male sperm. I am curious to know how they come up with this, since every other source is pointing in the 50/50 direction. Also, there was someone on this forum who applied for sperm ratio analysis and they asked in adwance the gender the couple is trying for. I suspect that this kind of information would affect their objectivity.
I would love to hear DR. Potter's oppinion as well.