The Jag originated in Norway, no the UK or America.
jags are a co-dominant morph of coastal carpet python that occured over in the uk (dont think it originated in america). to the best of my understanding, this occurred with pure coastal lines. since then, the laws in the uk have allowed them to be crossbred with several other forms of morelia for different behavioural and aesthetic attributes. some argue that there are no pure coastal jags as they were often crossed with smaller species like irian jaya or jungle carpet python to reduce size (it was my understanding, again, that jungles were more commonly used because of their brighter colours, but how would any of us really know unless we have been involved with this developing trend overseas ourselves).
Sye