If you have an angus, or any other breed, without markers for tendernes, What are the chances of haveing tender meat? Zero,Nada, Can't get there from hear.
These genetic marker tests are not an indicator of tenderness. Nobody claims they are. I agree with Dun, cut it or eat it.
It has also been proven that the animals with these genetic markers are more often tender than not. Haveing these markers does not mean they are going to pass them on. But without the markers they certainly can,t be passed on. Markers are only an indicator of the possibility or the probability.