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My Younger Sister Is Out of Control

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From the U.S.: I’m having major problems with my younger sister and I don’t know what to do anymore. She’s thirteen, I’m twenty, and I still live at home while going to school. Just a brief history: My sister is younger but much larger. She’s often had problems with obesity, while I’m very small. This has caused problems between us. Our parents got divorced about eighteen months ago, and it’s been very difficult. My sister had a hard time because the courts made her live with our dad part time and my mom just got full custody of her.

Anyways, my sister has been showing some very strange behavior. Over the past year, she has been consistently stealing my things. I know that’s normal for younger siblings, but it’s getting worse, to the point that she steals things she doesn’t need, like my underwear; I’m half her size. I walked into my room last week and saw that all my bedroom pillows had been slashed open, like with a knife. She’s also very volatile and blows up over small issues. She can’t keep herself or her bedroom clean. She has had a bed-wetting problem for her entire life, and she hides the used pull-ups under her bed. The odor is insane. She also eats constantly when no one else is here, like a LOT of food. Last night she told my mother that she hates me, wished that I would die, and that I’m the source of all her problems. My mother explained that I’ve been having problems with Bipolar Disorder and she says “Good, she’ll probably commit suicide then.” At this point, ever time she walks past me, she says something like “I hate you” or “B***”.

I don’t know what to do. I’ve tried talking with her, spending time with her, etc, and nothing helps. Her therapist suggested that my sister may be suffering from PTSD from events that occurred while spending time with my dad. I’m worried about her and about our relationship. Any advice would be greatly appreciated.

My Younger Sister Is Out of Control

Answered by on -


Your sister may not appreciate it right nowm but someday she’ll understand what an understanding and compassionate sister you are. From my point of view, this is the kind of situation that demands family therapy. You are correct that this behavior is not normal. She is sending up flares that something is terribly, terribly wrong. It seems that she is blaming you for her inner turmoil. In some strange way, that may feel safer to her than confronting whatever is really bothering her.

I would encourage therapy that includes your mother, you, and your sister. If something happened while she was with your dad, your sister needs to be helped to understand that you and her mom are there for her. Your mom needs help taking her role as the mom who is both in charge and in support of her younger daughter. You need new ways to manage all that hostility that is directed at you. Your sister needs support to tell you and your mom what is really going on with her.

To find a family therapist, go to the AAMFT (American Assn for Marriage and Family Therapy) website at:

Thank you for writing. Now take the next step and help your family get the help they need.

I wish you well.
Dr. Marie

My Younger Sister Is Out of Control

Therapists live, online right now, from BetterHelp:

Dr. Marie Hartwell-Walker

Dr. Marie is licensed as both a psychologist and marriage and family counselor. She specializes in couples and family therapy and parent education. Follow her on Facebook or Twitter.

APA Reference
Hartwell-Walker, D. (2018). My Younger Sister Is Out of Control. Psych Central. Retrieved on November 23, 2020, from
Scientifically Reviewed
Last updated: 8 May 2018 (Originally: 4 Jun 2014)
Last reviewed: By a member of our scientific advisory board on 8 May 2018
Published on Psych All rights reserved.