that's a good question but not necessarily pertinent to the shape and lines a car has. Look at Alfas of late (mito, giulietta, 147) the overarching design is one of femininity but i'd guess that the majority are driven by males. So much so that Alfa gave one of their flagship makes an outright female name and market it as a sexy blonde
Out of all the golfs the Mk5 by far and away has the most feminine shape and all the lines on it are feminine too. The Mk6 has a feminine shape but VW in their efforts to "face lift" the Mk5 gave it some masculine lines. I'd say the styling transition from Mk5 ---> Mk6 mirrors the Mk2 ---> Mk3 in reverse (i.e feminine shape given some masculine lines vis a vis masculine shape given some feminine lines).
For the record i'd guess and it's just my guess, GTI / Ed 30 / R series definitely = male majority. Bog standard golfs and GTDs = much more even between male / female owners. Maybe the office of statistics have the answer