I was born with my BDSM affinity. It is a trait a lot of us BDSMers are born with, not just human beings either. You find variations of that in many species.

By the way, the assumption that women are submissives/masochists and men dominants/sadists is idiotic. That is pure porn industry nonsense. I'm female and I'm a sadist, not a sub or maso. I'm in good and numerous company, a lot of women are - one way or other - tops (active roles in BDSM), just as a lot of men are bottoms (passive roles in BDSM).

The distribution of males and females amongst tops and bottoms is, when you look at BDSMers who come by their BDSM preference early in their lives (I was four years old when I knew what I am), quite even. I'm not denying that - especially among those who enter BDSM late and as sort of a lifestyle choice or from a merely erotic angle - there is a disparity between the numbers of men and women seeking passive and active roles. I also don't disagree with the idea that this can be and probably is largely caused by traditional gender roles, just like a lot of social roles and behaviour.

However, that doesn't mean that BDSM affinities actually are spread uneven. They aren't. It also doesn't mean that BDSM is negative or a result of brainwashing. You could just as well claim that being a lesbian is something society brainwashes into women.