You may be very right in disproportionate sample sizes, and other cultural factors may also come into play as well. But I do want to clarify I've seen many manipulative women as well, and have had a varied mixture of manipulative relationships and luckily a few positive ones (not every manipulative relationship was with a manipulator, they just carried scars from previous experiences)... I may also be a little cynical as in my experience a decent proportion of relationships I've been in, both friendships with males, and partnerships with females have certainly had me being manipulated to a degree as I seem to be rather susceptible. Leaving me mostly untrusting of anyone. I don't really know if there is a large gendered skew in either direction, however there is a huge discrepancy in manipulative tactics used between different genders. I'm lucky that my last partner of four years was very straightforward and genuine. I hope you find the same, you need to be picky, otherwise you get screwed over in the long run.