Decide how much of your sister’s superiority attitude you want to deal with. If you feel you are able to look past her actions and past behaviors, it is time to think about your current interactions. Past events in your shared childhood have led to the current state of your sibling relationship and you might not even see what has led to her attitude of superiority, states Jane Mersky Leder, writing for “Psychology Today.”

Look at the relationship you share with your sister. The two of you grew up together and, back when you were kids, she probably did not hesitate to tell you what she thought, writes Barbara Hannah Grufferman for "Huffington Post." That might not have changed now that you are both adults, particularly now that she feels she is better than you are. Now, instead of arguing about boys, you are probably arguing about careers and kids.

Remember the days when you were kids and think of shared memories. Those memories might not match each other. “I remember when you threatened to burn my hair with the curling iron if I wouldn’t stop wiggling!” “What? I never said that!” You are both convinced your memory is correct. It does not really matter. What does matter is that you are both treasured connections to your shared childhoods. Use this to change your current relationship, says Grufferman.

Consider the possibility of individual therapy. If your sister’s belief that she is better than you is affecting your relationships with other family members, discussing your memories with a therapist might give you the insight you need to understand your sister as you decide whether to continue a relationship with her. From a young age, you and your sister had already begun to carve out your roles, depending on how your parents treated each of you, notes Leder.

Suggest a time to sit and talk with your sister, recommends Grufferman. Before you have this time, think about who listens and who talks. You might already do both, but if you listen more, resolve to speak up. If you talk more, prepare to listen more. As a two-way street, communication is 90 percent listening and 10 percent talking. You might learn some facts about your sister that surprise you.

Examine your relationship with both of your parents, if they are still living. If your sister was treated differently from you -- even unintentionally -- this affected how you related to each other, points out Leder. Should your sister have been given preferential treatment, this would have taught her that, in your parents’ minds, she was better than you.

Think about any significant events that might have affected your sister’s attitude toward you, such as the loss of a pet, another sibling or parent, recommends Leder. You do not necessarily want to do this so you can open yourself up to more mistreatment. Instead, you want to have this insight so you’re able to make a decision about any future interaction or relationship with her.