where did roberts og kush come from whats the phenotype.
Any details of how Robert got his hands on the OG Kush strain would have to be told by him. He may have got his hands on a cutting or a select bunch of seeds.
Either way, you can only be guaranteed phenotype by taking a cutting. This is why some strains are not available in seed. The mother plant may never have been bred to develop reliable stable genetics expressed in seed form. And in that case you pretty much have to know the breeder personally to get a cutting in person from them.
When growing from seed, depending on the strains stability, you may discover a few of the different phenotype varietals yourself.