Any form of survey is taken with the explicit intention of tailoring a product or service of various forms to those genders.
I studied psychology at college, and I recall a lesson I had which explained that any survey taken would usually be considerably larger than needed - the reason being is they want the 'truth' from you.
e.g. if you had a survey asking:

What sex? M/F
What age? 20 - 40 / 41+
What car do you own? Big, medium, small

people would easily see the survey is about what types of cars people buy.

So, they confuse the survey by adding stacks of crap around the survey - thus removing the focus.