Is it normal that i lack empathy?

Is it normal that, even though I can put myself in other people's shoes and understand why they might be feeling a certain way, that I'm still not affected by their emotions? I can, for example, read into why a friend might be excited for an upcoming event, but that excitement doesn't transfer to my mood in the slightest, unless there's something in it for me. Even when the people I'm closest to and love most harbor very intense emotions, from joy to sadness, it never seems to alter the way I feel, unless it is somehow affecting me getting at what I want. I feel like I can read people well, so that isn't part of the problem. I can understand their thought process, why it makes sense they would be experiencing an emotion, but no matter how moving it may be, it can never seem to pluck my heartstrings. I still have feelings - there are friends and family I hold near and dear to my heart - but they're mine and mine alone, fueling me towards my goals, not stopping to weep over someone else's loss or celebrate another's success. Is it normal not to care like that?