Actually, it’s because of ‘center of gravity’. Women carry ‘weight’ literally in their hips. That’s where we balance from, that’s why the bones in our legs point outward from the knee up. Men and women aren’t that different in muscle strength, etc. BUT: The different center of gravity in a woman’s hips versus a man’s upper body will make it so its a cinch for women and men can’t rebalance their upper body while holding onto the chair.