I'm... fairly sure mine has? I'm not sure though. I know at 16, I had more male crushes than I do now. ('Course, all I have now is pretty much the desire to paw at David Tennant and Brian Viglione, but still, it is a very strong urge. =P) And I still hadn't noticed that I had the tendency to follow certain girls around like a puppy, or figured out why I got super jittery around some girls. (I kinda chalked it up to jealousy at the time, though "wait, do I like girls?!" was something that occurred to me on occasion.) Still, there were definitely dudes I found, uh, pretty. Brian Molko in makeup was my desktop for, like, ever in high school. Still, I think I liked... maybe three actual boys I went to school with in high school. Though this was the same period of time where I had a crush on a boy until he asked me out, and I then spent the next month avoiding him and shuddering when he touched me. I also had zero desire to sleep with him, even though my libido was through the roof. So, who knows? Once I sussed out the actual reason I tended to avert my eyes and get really nervous when faced with an attractive girl (either in real life or in media), I turned into a hornball pretty fast, haha.
I find it quite difficult to make a decision on this one. I like GhostDog would say I have less male crushes now, so I thought yes I think its changed, but then I wondered if I really had proper full blown boy crushes anyway, or whether I mistook slight attraction for a crush because before I realised I was gay I thought that was just how everybody felt and that that was a crush. Almost like I was forcing myself to have a crush because that was the right and proper thing for a girl to do. I think I remain undecided.
As others have said, it's hard for me to be sure if my sexuality has changed, or if I've just become more aware and/or accepting of all of its facets over time. I can be attracted to members of either sex, but I certainly had more attractions to men in the past (and in my case these were definitely genuine attractions, and I was quite capable of having relatively satisfying sexual relationships with men), while I feel much more attracted to women now. My girlfriend, for her part, swears that she never had any attractions, inclinations, suppressed crushes, etc. for women at all, until about 2 - 3 years ago when she was pursued romantically by a woman and decided to give it a try.
i'm going to bump this thread since the topic has come up recently and there a new members who haven't voted in this poll.
I think about it from time to time, I think I'm a little rare in that I enjoy penetration, but then I look at most men's bodies and I'm really turned off. They have to be really cut for me to appreciate their bodies. I guess I'm a looks snob in that repect. Trannies do nothing for me... so its a strap on or nothing.