It isnt random chance; something in your technique is spooking the females. Id consider your lure or urine use.
A similar case is with martens. Around here people mostly use tree mounted boxes and body grips. The catch is almost all males. The theories people come up with are enough to start eye rolling contests and fistfights; but it doesnt change that females either are scared by the box or lure, or don't like climbing, or are prone to evading trigger wires. The males are more aggressive. Put the box on the ground and use less aggressive lures and the females start getting caught. Mice start eating them too; but I digress.
Most people prefer catching the males and leaving the breeding stock for next years crop; so little experimenting is done.