You gastrocnemius does cross the knee (it is a weak knee flexor), so its use/disuse could be influenced by the condition of the knee and the angles it goes through. However, I would expect one to compensate for the knee by overusing the ankle (e.g. avoiding extending the knee by plantar flexion of the foot), not by underusing it.
You could also have a leg length discrepancy, which would influence how much you ankle with each leg. In this case, your right leg would be the short one, causing you to have to reach more by pointing your toes downward. it isn't uncommon for one leg to be logner than the other, and isn't that hard to fix. But you do need to diagnose it properly. This is just a logical guess.
Another possibility is that you are simply stronger or more confident in the right leg and consistently put out more power on that side.