johnny drama real name

In the Entourage program how Vince and Johnny Drama are brothers?

It seems strange in real life Adrian Grenier (Vince) is half the European average and native Kevin Dillon (Johnny) is white. When I began to see it done even seem motorcade the same ethnicity as I thought it had different mothers, but in the premiere of Aquaman episode that have the same mother. So I thought we had different fathers, but both of his name is Chase. Is there any reason or Adrian (Vince) is just for play as if it is blank in Entourage???

Because it is supposed to be Italian American. Some Italians may be darker than others. They could also be brothers.

Johnny “Drama” Chase (Jack Cooper)