I've always had geldings. I just recently adopted my first mare. Let me tell you what LoL she is a pain in the butt! She never pins her ears but she is pushy and has no respect. Our main goal right now is lots and lots of ground work and yielding from pressure. She has improved a lot just in a few sessions. I don't think it is a mare thing though. She is also boarded with an appy who does pin her ears all the time. A lot of people are scared of her and walk off when she does this. It's a bluff. She learned early on that she could pin her ears and humans would go away. If you continue what your doing or even just sternly saying her name, she perks her ears back up like it never happened. It's not because she is a mare either. Horse's have personality quirks just like we do. I can not tell you why your mare does what she does but it's not because she is mare IMHO. I hated mares until I realized they aren't all that bad after all.
good luck figuring it out