>A "better" ratio of THC:CBD

Here in Florida I think CBD oils were recently legalized and I think a single strain of marijuana (with negligible THC and high CBD) had been permitted for epilepsy patients. To be honest I haven't followed to closely after the last medical marijuana bill didn't pass.

Anyway, is the CBD/THC ratios interdependent? Meaning as one goes up, the others go down? Or are there some strains with significant amounts of each and others with low amounts of each?