This is absolutely true, as with everything, there is a genetic component.
However...
Every single instance of a "low responder" that I've seen, meaning someone who gets little to no progress from moderate to aggressive dosages, or individuals who "require" aggressive dosages to progress have had serious lacking in their nutrition, training, or recovery metrics.
Even to take
@Juicedhead as an example, openly admitted he cruises on higher doses because he relaxes on his training and diet during cruise periods and need those extra drugs to pick up the slack.
Individual response is absolutely variable person to person, but I do not believe it's anywhere near the level as some people make it seem.