Because this does not fit with my perception of human behaviour, but it does fit animal behaviour.
That seems like an admission that all you have is personal incredulity: it doesn't seem like it could be to you, so it can't be.
You claimed before you had logical reasons for what you believe, your subjective perception isn't logic, so what are they?
I don't really even get why your perception is as you say. You can't control what you want, can you? You can't suddenly decide to dislike something you love, or to like something you find unpleasant. You can't control what occurs to you at any moment or what you are reminded of by events. How can you possibly "perceive" that what you want at any moment
cannot possibly have been determined by past events?
Past events would include all your nature and all your nurture (including the nature and nurture of any soul you may postulate), all your experience - everything that has made you the person that you are. If what you want is not determined by those things, what else is left?