Why do you adress this question to me? I don't know how many Kenyan runners cheat. I don't know how this number compares to them of the other leading nations.
I havn't read any papers to the subject, I just can speculate.
Kenya has much more top class and 2nd tier runners than probably any other nation on earth. If there is the opportunity (lax testing until resently) some will use it. To reach the top even in your own country is extremely hard in Kenya. The incentive (a lot of money) is extremely high. Probably nobody on earth cares about a Kenyan 1:46 800m runner, sub 1:45 and you will get good opportunities.
Do they have less morality than Europeans? Maybe, maybe not. But I doubt it, just look at the Tour de France. Look at all the European managers and doctors who are behind such trends.
These are just some thoughts. But - again - why are you asking me this?