Do me and my siblings act this way toward each other because of our Zodiac Signs?

Yes indeed you do. However never forget that we learn many heavy life lessons through our family. You are an Aries. Quick to battle and don't take crap from anybody. You are surrounded by water signs with Cancer sis, Scorpio sis, Pisces brother. All that water and you are fire. No wonder you don't get their behavior at times. You are action. They are emotion. Your Scorpio sister is able to see ones weaknesses and so during a battle this information is used for hurtful purposes. As she is usually spot-on. Cancer women tend to fall in love with the underdog. She is sensitive and caring and nurturing often to others not deserving of her attention. Best for her to move on but until she learns this she probably will keep making the same mistakes regarding others: One must never believe what another says. People can say anything. It is best to watch their behavior as this always reveals the TRUTH. Cancers and Pisces esp need to learn this as they love with their hearts and not their heads. You brother is probably sensitive as emotions run deep in Pisces. As he ages he will become more outgoing and less annoying, unless he gets hot-headed and arrogant. Be watchful of him and give him direction as he will need it. Pisces do not tend to have much common sense. That is why he will need sound advice as he grows. Usually siblings get closer as they age. But always love one another. Never exclude one another. You are family for better or worse. Good luck to you all and Bless you all too.