haha, no need to be sad, it is pretty common to not have it i think Rick Beato has some videos on this on his YT channel. you might want to have a look there. in my opinion, you can probably spend your time with more useful exercises, most musicians don't have it, and don't need it.
My daughter has it and it’s freaky. You can play any note from the other room and she tells you what it is. Then ask her to sing any note and she nails it every time. She tells me all the time when my bass is slightly out of tune.
Answers
I think possibly you could develop it over time.
I think its probablly inbulilt - just there - but you can learn to hear the notes with practice I guess .
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