Hi Linda. You are correct about opera singers singing pop/rock. No matter what they sing they will always sound like opera singers. I would imagine the same in reverse. A rock singer eg Freddie Mercury could never truely sound like an opera singer and the example you gave bears this out. Freddie is good at Barcelona but it is not opera. Vikki nearly hit the nail on the head talking abot body builders trying ballet. Perhaps a better example would be a pro tennis player taking up golf. Whilst his hand to eye coordination is very good the disciplines and techniques are so different he would struggle without the proper practice and dedication. He might never make a pro golfer and even to participate at a reasonable club level could take many years.
Can pop/rock be taught? I suppose so as just about anything can be taught. I am of the feeling that to excel in any field you have to have a certain natural ability first plus the necessary dedication spending many years perfecting your gift. You learn by your mistakes. Tuition can improve/hone this talent but it cannot magically produce talent that is not already there.
Remember school. There was always a couple of kids who excelled at say sports or art or academics and a couple of kids who were complete duffers no matter how hard they tried. All the kids had the same tuition. The difference, natural ability.
When you see people clapping along to a song at a pop concert there are always a few who are completely lacking in any rythmn yet the rest can do this simple thing easily without even thinking.

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