Even though they share a room, Jennifer, 15, hasn't spoken to her sister, Nicole, in more than a week. "Nicole is always taking my clothes and wearing them without asking," Jennifer complains. "Last week was the last straw. I found my new sweater tossed in the laundry room, and it had a big stain on it. When I asked Nicole about it, she acted like she had no idea what I was talking about."

Ryan, 16, says he's tired of his younger brother, Sean, 13, hanging around when his friends are over. "He's such a pest," Ryan says. "Every time my friends come over, Sean turns into my shadow and wants to do whatever my friends and I are doing. I wish Sean would find some friends of his own and leave me alone."

Sources of Conflict

What makes siblings get on each other's nerves? Lack of privacy is one factor. "When living in a family there is generally a lack of privacy for everybody," says Dr. Clifton Saper, Ph.D., a family counselor in Elk Grove, Illinois. "That's not usually a problem for young children, but, as kids hit adolescence, privacy becomes more of a issue."

Maybe your brother eavesdrops whenever you make a telephone call. There may be nowhere to go for peace and quiet when you need to do your homework. Perhaps your sister sees nothing wrong with invading your bedroom closet and taking your possessions without asking.

Age differences have a part to play. "The difference between a 16-year-old and a 13-year-old in interests, capabilities, freedom and activities can be huge," says Dr. Peter Goldenthal, a family counselor in Devon, Pennsylvania, with a special interest in sibling rivalry. "Typically, older siblings want to differentiate themselves from the family, so they're not that interested in hanging around with their younger brother or sister."

Tim, 16, says he just doesn't think he has much in common with his 12-year-old sister. "My little sister, Emily, keeps bugging me to play games with her, and she acts all hurt and upset when I say I've got other things to do," he says. "But I just got my driver's license, and my friends from school want to go places with me, so what can Emily expect?"

Competition and Fairness

Siblings who are close to each other in age often view each other as rivals and may compete with each other for friends and popularity, academics and athletic accomplishments.

"My sister, Kelly, is just a year younger than me, and it seems whatever I do she does the same," says Amanda, 17. "When I decided to try out for the lead in the school play and Kelly found out, she decided to try out too. When I took up tennis, Kelly also learned to play. She seems bent on proving to me that, even though she is a year younger, she can still do anything I can and better."

Another cause of sibling conflict is perceived unfairness. "One sibling may think the other is getting more than his or her fair share of attention, privileges, space or other perceived limited resource," says Dr. Charles Thompson, professor of counselor education and counseling psychology at the University of Tennessee.

There may be only one car or computer at home, and you think your brother gets to use it a lot more than you do. Or maybe you feel your parents are tougher on you than they are on your younger brother or sister.

"The older sibling is the first to enter high school, to ask for a later curfew and to drive a car," says Dr. Mary Halpin, an adolescent counselor in Deerfield, Illinois, "and typically parents are more cautious with firstborns because they're inexperienced having an older teen, and so their rules are stricter.

"Then, when the younger sibling comes along, the parents are usually more relaxed with the high-school scene, and so they allow the younger one more leeway, and the older sibling thinks that's unfair."

Making the Relationship Work

There are bound to be minor tiffs now and then, but there don't have to be--and shouldn't be--frequent blowups and tension. Relationships with your brothers and sisters should be supportive and strong. Here are some suggestions for improving the relationship you have with your brother or sister and becoming better friends:

• Change your perspective. If your younger sister says, "How come you always have time for your friends but you never have time for me?," before you get defensive or angry ask yourself some questions. Is it possible that the statement is not criticism but really a way of saying "I care about you"?

See if you can understand what your sibling is trying to get at rather than immediately replying with a negative comeback. Challenge yourself to try to understand what's going on in your brother's or sister's life.

If you have younger siblings who follow you around, realize they're not trying to make your life miserable. "What usually happens is that younger siblings tend to idolize the older siblings, and that's why they want to follow in their footsteps," Dr. Saper says. "They very often see him or her as a role model."

Understand that your younger sibling is so pesky and doing everything you're doing because he looks up to you. Try to find some ways to include your younger sibling in your activities every once in a while and he will feel less need to pester you for attention.

• Don't compare yourself to your sibling. You may look at your brother's abilities and think to yourself, "It's not fair; he's better than I am at everything." But realize he may be thinking the same about you. Everyone has talents, and no one will succeed in everything all through life. Let your siblings shine in their own areas of strength. Rather than wish you had the same strengths and abilities as your brother or sister, look for your own talents and strengths and work on developing those.

• Give your sibling some space.If you are sharing a bedroom with your sister, sit down with her when you're both calm and come up with a system of rules for the room which both of you can agree on. "For this to work, both siblings have to be mature, sensitive and willing to negotiate and make compromises," Dr. Goldenthal says.

Make it a rule that you will not borrow each other's things without asking. Set aside a time for quiet time each night so you can get your homework done. Allow each sister to have some of her own wall decorations. You might want to designate certain areas of the room as being one girl's. Talk about how you will handle situations when your friends are over and you want to talk with them in your room. Once you agree on your rules, stick to them.

• Build positive interactions. Rather than always focusing on resolving conflicts all the time, ask your sibling to take part in some kind of fun, noncompetitive activity with you.

Go to a movie or take a walk together. Spend several hours at the park or pool. Treat your sister or brother for a sundae at the ice-cream shop. Give yourselves a chance to do something enjoyable and positive with each other so you're not always quarreling and getting on each other's nerves.

• Look at the long term.During your teen years you may have interests that are quite different from those of your younger siblings, and life with them may seem intolerable at times. Try to look at the big picture. Realize that, no matter how frustrating life with your brothers and sisters can be right now, it's not always going to be that way. "Many adults who are close to their brothers and sisters will tell you they didn't get along with each other growing up," Dr. Thompson says.

Chances are, your siblings will be the ones you turn to for help in your adult years. Unlike friends who come and go throughout your life, your siblings are always going to be your siblings.

With patience and understanding on both sides, you might find that your brothers and sisters are a good source of support and advice. The Bible even tells us that "a brother is born to share troubles" (Proverbs 17:17, Revised English Bible).

Granted, it's no fun when your little brother reads through your diary or your sister helps herself to your clothes. It may seem hard to believe, but years from now as adults you and they will look back at your teen years and laugh about the stunts you used to pull on each other. For the present, try to have a sense of humor and apply some of the tips in this article. If you do, things are bound to get better. GN