I suppose my first exposure to the fact that people have different inborn listening abilities came about when I realized that I didn't have perfect pitch. In most families the odd person with perfect pitch is considered the exception, but in my family I was the only person who, without a relative measuring pitch, couldn't tell a G# from a G, or pluck one or the other out of thin air. My father claims not to have perfect pitch, but I believe that his perceived lack of perfect pitch is only "relative." He is right most of the time. I have never known him to be wrong. My mother, all my brothers, and the two grandparents (one maternal and one paternal) I knew all had absolute perfect pitch. I tried for years to develop it, even going to the extreme of waking up before my alarm clock sounded its electric B-flat buzz to sing what I thought was a B flat, and see if I was right. Somehow that pitch remained in my brain, but only in its electronic voice. On an acoustic instrument or a voice a B flat could be any one of its chromatic neighbors to me. Developing dependable pitch memory would be equivalent to the task of trying to be taller than five feet one (and a quarter).
My vastly imperfect pitch has come in handy from time to time. I don't have any problem playing baroque music at A=415 (on any instrument), and transcriptions never bother me.
I assumed that anyone who wrote music had to have perfect pitch, and I assumed that anyone who wrote the complicated music that was new when I was young could hear all the pitches, separately and in combination. The people I spent time with, particularly the composers who were at Tanglewood during the 1970s, could hear everything. They were kind of superhuman, but I thought they were normal. There was some new music (in the 1970s and 1980s) I could grasp, like music by George Crumb and Olivier Messiaen, and most Ligeti, but it was really difficult for me to claim that I really could "hear" Sessions, Carter (music he wrote during the 1960s through 1980s), and Babbitt.
I have no ear for microtones either. None. As much as I like Ben Johnston's ideas, rhythms, textures, and sonorities, I just don't get the microtones. My imperfectly-pitched ears tell me that microtonal music is out of tune (while my objective mind tells me that the playing is correct).
Just because I can't hear microtones doesn't give microtonal music lesser worth in the grand scheme of things, and just because I don't have the vocabulary to evaluate the quality of one mid 20th-century serial piece against the quality of another, doesn't mean that there isn't quality to be evaluated. I don't understand the stock market, politics, or mathematics beyond arithmetic, and I know that those things have serious merit and enjoyment for those who do.
I would love to have perfect pitch for a day, or a week, or a month, so that I can have the serial music and microtonal listening experiences that many mid-to-late 20th century composers intended their audiences to have (I suppose I would have to have perfect polyrhythm as well in order to really understand Babbitt). Perhaps my beloved tonal and regular rhythmic world would be tossed on its ear, and perhaps I would never be able to enjoy its limits again.
Perhaps I'll just keep the ear I was born with.