Different people react differently. The first dead I saw was a women, falling to her death from the 9th floor. I was 3 at the time and there was no revulsion, just curiosity I guess. Maybe just because I didn't have enough of understanding of 'death' at that time.

I've seen people die (or dead already) many times since then and... It doesn't really make you sick. The unpleasant feeling is still there, yes, but it's more about disgust than anything else.