In regards to the liger, it has to be a female tiger and male lion. This is because the trait that determines size (limits growth) is present in the male tiger and female lion. When the female tiger and male lion are crossed, their offspring lack this size limiting feature and hence grow to enormous proportions. It’s most likely a pituitary defect...the same kind present in many super tall humans (7ft+). If you look at a Liger, many of its features are distorted....this further supports a pituitary issue.
But that is a side point.
In regards to GG, I will agree with the majority of the posters and say most GG blood has been incredibly thinned in American breeding stock. Most large dragons are likely due to selective breeding, and not GG blood. I have a 24" male named Oscar, and was told he had GG blood. Knowing how long ago true GG hybrids existed, Oscar's size is most likely due to good genes. He is 15 months old and around 550-600 grams.
Being a roach breeder, I have the pleasure of noticing generational changes at a much faster rate than bearded dragons. Roach breeders have to be mindful of their average roach size shrinking, as smaller males mature faster and hence breed faster. I recently traded stock with several other breeders, and was astonished at how small their roaches were. This may be due to them purposely sending me small insects, or it could be due to lazy breeding. Either way, through selective breeding (removing all small males), I have managed to maintain a large size roach. The same is most likely true for bearded dragons (selective breeding) that are referred to as GG. GG is nothing but a marketing tool nowadays, and I doubt any GG sold today has more than 1/16th P. Barbata.
Do I wish the US stock could receive a nice boost from true GG? Yes I do, but I also know that would mean another species of animal being exploited for nothing more than retail gain. I fully support all export restrictions placed on Australian wild life, and wish there was a way to protect more of their native species....such as P. Barbata. I would like to see some breeding regulations placed on US dragon breeders, but that is unlikely to happen. Its great bearded dragons make such nice pets, but unfortunately this means the species will continue to be exploited for nothing more than money.
I really shouldn’t judge however, as I make a good portion of my income feeding these animals, and saying the above makes me sound like a hypocrite.
I should clarify that I was referring to the shady breeding operations that purposely turn out these mutated morphs, or don't care at all about their reptiles. The breeders present at BD.org all appear to actually care about the animals they are selling.