Dear Annie: I have an 18-year-old twin sister. We have the same friends, the same classes and the same extracurriculars.

The problem is, she bullies me. If I have something she wants, she throws things at me. She pushes me out of my chair so she can sit in it. She constantly teases me, even when our friends are over.

Everything I do, we do. Everything we do, she’s the boss. If I resist, she hits me. We have an older sister, but she favors my twin. My friends don’t want to get involved or are oblivious to it. My parents do nothing. It’s obviously hard to avoid her, and I’m tired of sinking to her level. What can I do? – Twin Problems

Dear Twin: This is extreme sibling rivalry. Bullies are often jealous and insecure. Talk to your school counselor. Then look into switching classes and extracurricular activities so you are not together. Make different friends. Be sure to attend different colleges. You and your twin need to separate yourselves and develop independent interests so she no longer feels so threatened by you. And she needs to grow up.

Dear Annie: My son and his girlfriend, “Mandy,” have a beautiful baby boy, “Cal,” who is my first grandchild. Mandy also has a daughter, “Lila,” from a previous marriage.

Lila used to call me “Grandma,” but recently began calling me “Grandma Kay.” I am worried that Cal will start calling me by my first name, too. I asked Mandy to have Lila simply call me “Grandma,” but she refused. – Just Call Me Grandma

Dear Grandma: Where is your son in all this? You should be registering your complaint with him, not Mandy. That said, however, this is not such a big deal. Many children use “Grandma First Name” to distinguish one set of grandparents from the other. It is not an insult and is no reflection on how close and loving the relationship is. Please don’t make a fuss over this.