Some studies say it does, but the result is inconclusive because it depends on the region. For example, people living in mountainous regions will fare better if events are hosted in their areas but if the event is hosted at sea level, the body might 'de-train.'
On the other hand, geography gives Kenyans a structural advantage that sees them excel in long distance events. But to maintain this advantage, they have to reside there, and return to sporting locations in time to acclimatize.
The result of this advantage is a sum of all the factors and not just one. That is why is should be so but not always so.