I swear I saw this guy on a documentary called "You Don't Know Dick; Female to male Transsexuals" It's insanely interesting - my favourite bit was this new female-to-male man who explained how previously, as a lesbian woman, she had been quite politically aware of how many women felt oppressed by men and/or used for sex.
But when she started to take testosterone, she said, everything changed. She said something like "I just wanted to fuck...it was like, relationships are great, but let's talk about that later because I just wanted to fuck every woman I saw".
I guess it really is a hormonal thing, and I thought it took a lot of guts to say it given the chilly reception such a statement might receive from the more-oppressed-than-thou feminist types.