Do you know of other apiaries in the area besides yours? What types of bees are kept there?
There are more feral hives out there even if no other managed. New queens from your hives will go out to a drone congregation area well away from your apiary...there could be drones from 10 miles away there. With just 7 hives, your drones make up a small fraction of the drones in the local DCAs, so odds are very good that your queens won't mate with drones from any of your hives.
As said below, once you have a mated queen, her female offspring will be be 50/50 her genetics and those of the drones she mated with. So all of the workers share half of their genes with the queen, but there are several fathers - like a family of half-siblings. The drones have no father, all of their genes come directly from the queen.