Why does porn make you want to have unreal nookie?

Since i started watching it in my early teens i ve progressed from liking simple boy/ girl, to threesomes, to various unusual sexual acts, to transsexuals, to women of different races, to fem dom and female worship, impregnation fetishes, pregnant women, much older women (even grannies), teens, even some bi sexual stuff, i feel like i ve been exposed to a lot of things that i wouldn't have normally been exposed to and i have developed a taste for all these things and probably a few i have forgotten, i enjoy a different fantasy once or twice a day, question is for me would i have been into these things if i hadn't been exposed? Would i have a desire to do these things in real life? Have i and many others been brainwashed?