I dont think its gender specific... could be just getting use to the weight, recoil and anticipated "boom" of the gun. I know I have NO upper body strength so when I first started I was shooting heavier guns I would lean back to give myself more leverage. Also another thing you will notice is the hold..some people will hold the gun near the bottom.
Try having your students do more of a squat over emphasizing a stance could help them find a comfortable middle ground.
Another stance you can have your students try is what is being taught by civilian arms training. http://www.civilianarmstraining.com/
It seems a little scary to have the gun closer to your face but ergonomically it is very comfortable....