the sheep and goats meant that i was a goat

are you talking about the parable?

the article was about singing, the author and other people were asked to sing up and down a scale, then the author was told that he was not good at singing, i was wondering if there is any denotation.

here is the parable

http://www.gotquestions.org/parable-sheep-goats.html

without the full context of the sentence I'm not 100% sure it applies, but based on the clue you've provided it makes sense

Yes, I think I got it, thanks a lot!

I don't see any reference to singing in that parable.

Anyways, goats are hella smarter than sheeps.