There is no legitimate excuse for rudeness, but when that behavior is exhibited by relatives, it may be difficult to avoid. It can also be uncomfortable to confront a family member, despite their apparent lack of concern for the feelings of other people. In some cases, you might feel trapped because you have familial obligations that force you to interact or be in the same room with a relative who is rude or insulting. You can't choose your family, but you can choose how you deal with those members who seem to thrive on being rude and hurtling insults.
Avoid conversation with the family member who tends to be rude or insulting. While you may attend the same family functions, you aren't obligated to have a discussion with someone who is disrespectful. A simple greeting and handshake may be sufficient, and staying out of earshot can help diffuse your anger if the individual inflicts his or her bad behavior on someone else. It might also help to remind yourself that people who are rude or resort to insults are often insecure or feel threatened in some way. This doesn't excuse their bad behavior, but can change your perspective and reduce reactivity.
Confront the relative who resorts to inconsiderate behavior. Typically, every family has at least one member who is less-than-tactful in their approach to communication. Family members may not feel comfortable saying anything, however if nothing is done to condemn the behavior, it is being condoned by silence. Schedule a convenient time and quiet place to have a frank discussion with the relative who is rude and insulting and explain how their behavior affects others. Refrain from interjecting judgment, although this is sometimes difficult with someone who is rude.
Kill them with kindness. It's not the easiest approach but responding to rudeness or insults with a kind smile and pleasant demeanor can diffuse them. Being respectful and kind can also help you feel less stressed when you're in the presence of that particularly troublesome family member. If the family member isn't getting a reaction from you, they may simply stop trying. You can also use this approach to be an example for good behavior, in contrast to the inappropriate behaviors exhibited by your relative.
Speak to other relatives who might have a better rapport with the family member who is rude and insulting. Although you are related, you may not be the relative who is closest to the poorly behaved family member. If someone else in the family appears to have a closer relationship, speaking with them privately about your concerns may provide them with a perspective they might not otherwise have. After explaining the behaviors and how they are affecting you, it's also helpful to provide a reasonable expectation.