I think people are born with their sexual instincts inline with their anatomies and sex identities, but these can be altered so that a persons instinct can be compelled to go in another direction.
I once read an interesting account of a person who had abuse from a person that built fires in the woods at the same time as the abuse. This person grew up to have arousal from fires and got in trouble for arson. In truth though I don't think the person could have helped themselves right off. People who undergo traumas can be compelled to be attracted or repelled by things related to the trauma. So I do believe its often traumas/neglects that influence some peoples sexual urges.
There is also the issue of bonding which sometimes gets scoffed at as "simplistic" but Einstein said the laws of the universe are so simplistic they are hard to see and over-looked.
I know people who raise wild animals will tell you that if they want to domesticate a wild animal they need to get it away from its mother right away before it gets "imprinted" with its identity. A baby monkey can also be taken away from its mum and put in with ducks and it will think it is a duck.
Indeed a animal psychologist named Konrad Lorenz won a Noble Prize for his studies of "imprinting" and geese. He used to get geese and ducks to follow him around thinking they were his mother (that's him in pic below). I think people can also get imprinted in ways that steer them away from their core identiy.
So, in view of those observations I think people can be driven to certain identities in ways they can't always control if at all. But I don't think people are born that way. I know people who feel compelled to get taken advantage of in very destructive ways and they often think they just like things like that when they are acting out impulses not organic to them. However I have also found there is also something of fad (mostly among girls) with people declaring themselves to be some sexual pedigree that they often abandon latter.
