Choose the right time and place to make an apology. Vice dean for faculty and administrative affairs at Penn State's College of Medicine, R. Kevin Grisby, D.S.W., says that most apologies should take place in a private setting out of respect for the individual who's been wronged. This allows your brother or sister to deal with a sensitive matter away from others. Furthermore, offer your apology at a time that's convenient for your sibling.

Acknowledge your sibling's feelings. Be sure that you understand how your sibling feels after you hurt her, and clearly address these feelings. Clinical psychologist, psychoanalyst and author Joseph Burgo, Ph.D., suggests that you refrain from using the words "if" and "but" when acknowledging your sibling's feelings. For instance, a statement like "I'm sorry if you were hurt by what I said, but you hurt me first" diminishes the sincerity of your apology by devaluing your sibling's feelings and justifying your hurtful behavior.

Take responsibility for your actions. Speak honestly about your behavior and apologize to your sibling for causing him harm. Use a statement such as "I apologize for my behavior last night - I realize that I was out of line, my behavior was hurtful and I am truly sorry for causing you pain," because this both acknowledges your sibling's feelings and allows you to take responsibility for your actions. Resist any urges to mention your sibling's behavior - focus only on your role in the conflict.