It is completely unjustifiable to judge a bowled based on what other bowlers of his type from his country have done, though. Chawla isn't going to be intrinsically better or worse depending on how many leg spinners India have produced - it's not really at all relevant to how good a bowler he is.
I frequently give the benefit of the doubt one or the other when talking about Indian pace bowlers for example. If there is a history of a country not producing a certain type of player, there is usually a reason behind it and generally it requires an exceptional player to come out and break the stereotype. That doesn't mean that Rashid is not the exception, but based on past experiences, there is something which causes the English leg spinners to taper off, or not to become world class as often as those from other countries. Again, Rashid may very well break that chain, but IMO it is not unreasonable to have doubt until he actually does it.
Same with the Indian pace bowlers. Really, it applies to all players from all countries. It's just that sometimes you give the benefit of the doubt to one player over another based on that countries history of producing that type of player. Example: if its a batsman coming out of India, without seeing him, if you ask me to rate him, I can generally be relatively confident that he won't suck against spin. I'll be less likely to give him the same benefit of the doubt if you ask his ability to play pace at Perth. Now the best player of spin until last year was from the West Indies so obviously these aren't rules, but more of 'personal guidelines to temper your initial excitement.'
Obviously, doing badly or well in any of those situations would cause me to change my mind.
Being born in Yorkshire doesn't make you any more or less talented than being born somewhere else, but countries do differ in terms of how they develop, encourage and build the spinners. In many countries, captains ruin spinners at a young age by not setting proper fields, forcing them bowl defend, not get proper coaching, the pitches aren't conducive, etc. The talent levels might be the same, but the development may suffer. So it just means that a kid from Yorkshire would have more to overcome, compared to someone from maybe Kandy who gets almost tailor made pitches and a captain knowledgeable and willing to put up with a style of bowling.
Same thing with fast bowling and India. No fast bowler in India likes bowling after the 10th over, and captains can't wait to get them off in favor of a spinner as soon as that ends...it would be insane to say that these things have no effect on the chances of a player succeeding, regardless of their talent level. Even at the FC level, and especially the club level, the attitudes and knowledge can differ extensively which has such a huge effect on someone's chances. Look at someone like Powar. If I saw an 18 year old kid bowling the way Powar does, one in India and one in New Zealand, I would say the guy in India probably has a chance to be more successful over the long term. The kid from New Zealand might get tonked around a bit and the captain would probably lose confidence much early, or he'd end up bowling flatter and faster to try to stop it. It's just much harder in some places than in others.