AITA For Setting a Curfew on My Sister, Protecting My Baby’s Sleep?

Jonathan Hours
Comments 0 Comments

Imagine a cozy apartment, a baby finally drifting to dreamland, only for a shrill keypad beep to shatter the silence—again. That’s the nightly saga one young mom faced when her college-aged sister, Mia, turned their home into a late-night obstacle course. At 25, with a fiancé and a six-month-old son, she opened her doors to Mia, hoping for harmony. Instead, she got sleepless nights and neighbor complaints, pushing her to a breaking point.

This isn’t just about a noisy lock; it’s a tug-of-war between sisterly kindness and a mother’s fierce need for peace. Each beep tested her patience, turning generosity into frustration. When Mia’s drunken fumble triggered an alarm at 4 AM, the mom drew a line—a curfew for her 20-year-old sister. Was it a fair boundary or an overstep? Reddit’s weighing in, and the debate’s as lively as a midnight alarm.

‘AITA for “grounding” my adult sister?’

I (25F) live in a three bedroom apartment with my fiancé (27M). We have a six month old son. My younger sister Mia (fake name; 20F) recently started attending a university that's closer to where I live than both my parents' places. Because she needs to get to class early in the morning, my fiancé and I allowed her to move into our spare bedroom.

She's been living with us since January. There's a set of rules I've been having Mia follow since she moved in, mostly to make sure everyone can live peacefully. One of the most important rules concerns arriving after my son's bedtime (usually between 19h and 20h). Mia is allowed to come home however late she wants, as long as she doesn't make too much noise.

The door to the apartment has an electronic keypad lock, and the one we use also has a normal lock under it. Everyone has a copy of the key, but we all prefer typing in the password. However, the keypad is very noisy, and my son's nursery isn't far from the door. Every time the keypad is used after I've put the baby to sleep, he wakes up.

So naturally, the rule about getting home late includes not using the keypad. Everyone, including Mia, has known about this since day one. At first, we had no problems. But now that Mia has gotten used to college life, she's been going out at night frequently. This past month, she has arrived home after midnight every Friday and Saturday night.

She always forgets the

She agreed, and promised to try to make less noise. On Friday night this week, Mia went out with her friends. She came home very drunk at 4AM, and forgot that I'd changed the password. Not only did she use the keypad, she also got the password wrong so many times that she triggered an alarm.. I was furious. Not only did my baby wake up crying, but I also got complaints from my neighbors.

The next morning, I told Mia that I'm establishing a curfew: while living with me, she needs to be home by 20h. She won't be allowed to go out at night for the rest of the semester. Mia put up a fight, saying I have no right to

I told her she'll be free to do as she pleases when she has her own place and raises her own family. While living with mine, she has to do as I say. She told our parents about this. Our mother and stepfather are both on my side; our father is on Mia's. He's saying I'm not her mother, and I have no right to treat her like a child. He also thinks it's unfair to do this to her over a drunken mistake.. AITA?

Living with family can feel like a warm hug—until someone’s late-night antics turn it into a headache. This mom’s curfew for her sister Mia, sparked by repeated disruptions, shines a light on the delicate dance of household boundaries.

Mia’s keypad blunders, especially her drunken alarm fiasco, pushed her sister to prioritize her baby’s rest over Mia’s freedom. The mom’s frustration is clear: she offered a home, not a free pass to chaos. Mia, caught up in college life, seems oblivious to the ripple effect of her actions. Family therapist Dr. John Gottman notes, “Respecting boundaries is key to healthy relationships, especially in shared spaces” (Gottman Institute, 2024). Gottman’s insight highlights the mom’s right to set rules—Mia’s not a child, but her choices disrupted the household’s core.

This clash mirrors a broader issue: navigating adult sibling dynamics in shared living. A 2023 study by Apartment List found 62% of young adults living with family face rule disputes, often over noise or schedules (Apartment List, 2023). Mia’s resistance, backed by her dad, suggests a struggle to balance independence with accountability.

Dr. Gottman advises clear communication and consequences—like a temporary curfew—to reset expectations. The mom could try a compromise, like reinstating keypad access after a month of compliance. Readers, have you tackled similar family friction? Share your tips below.

Heres what people had to say to OP:

Reddit never holds back, and this story stirred up a buffet of opinions—some spicy, some practical. Here’s a taste of what the community dished out, with a side of humor: These hot takes make you wonder: is a curfew the ultimate boundary, or just a shortcut to family drama? What’s the real fix here?

puntacana24 − NTA - I admit it does sound like a bit of a power trip to “ground” your adult sister, but it is well within your rights to enforce rules when you are allowing your sister to live there apparently for free. If she wants full freedom to do whatever she wants, she can always rent her own place. If she’s in college she’s definitely old enough to have some responsibility.

ToughDentist7786 − NTA, though “grounding” a 20-year old is not really a thing. I think since she can’t seem to function normally when she drinks, on those nights she just needs to crash at a friend’s place. I think next semester she should get a house with some friends. She would just have a much better experience her last two years of school.

SushiGuacDNA − NTA. Oh man. When I read the title I was ready to rip you a new one. Don't infantilize an adult woman! You didn't become her Mom just because she moved in with you.. How wrong I was. She lost her right to come in the house late when she woke up your child over, and over, and over. You were flexible and let her come in late as long as she didn't use the keypad.

She abused that, and abused it again. Instead of grounding her, you made a very reasonable change:

As long as you are treating her like a child (well deserved!), you might consider that a common technique with children is to ground them for a while. Like, maybe after a month give her another chance. But then if she does it again, it's two months. Or whatever details make sense to you. You wouldn't be an a**hole if you don't do this, but it might be nice and it might get the rest of your family off your back.

friendlily − NTA and you've given her *way* more chances than I would have. I would tell her that if she wakes the baby up one more time, she's out. I can't imagine how annoyed your husband must be that you keep letting your adult sister act like an entitled 16-year-old.

mfruitfly − NTA. Your sister may be an

If she lived with roommates off campus, without adult supervision, then sure, there would be no baby to wake up. Would she and your father prefer her in that environment? Because if your father wants her to be treated like a full, independent adult, he can pay for her to live in that environment and would also probably worry that his baby girl could be unsafe.

Your sister is in that weird in between time in her life, and that is why a lot of college kids live in dorms, to explore their own stupidity safely (aka getting drunk, fighting with roommates, learning boundaries, all while having a structured environment like campus safety and resident advisors).

I do think grounding/having a curfew is a tough one, so I'd counter with an alternative: Keep it so she doesn't have the passcode, only the key, and tell her and your father that if she wakes up the baby with the keypad (which she shouldn't be using since she doesn't have the passcode), ever again, she will need to find alternate housing. That's treating an adult like an adult- clear rule with consequence, assuming the person can act accordingly.

[Reddit User] − He's saying I'm not her mother, and I have no right to treat her like a child. Sounds like your sister has a new place to stay. Tell her to pack up and move in with Dad. Let her know she should have an easier time living with him since he feels like people don't have the right to set rules in their own home.. NTA

Forward_Squirrel8879 − NTA - You are not

ShinaSchatten − NTA. At this point, I would ask her when she's moving out.. Either she abides by your reasonable rules (which she has proven she cannot) or she moves out.

Beautiful-Contest-48 − For everyone posting here to put a post it note, stop treating her like a child or she should be quiet because there’s a baby I’m going to say this. In any situation I’ve ever been in where I come home to someone sleeping, my fat ass (440lbs) is stealthy quiet.

To the point of them not even knowing I came home most often. It’s basic f***ing manners. Why are some people just dicks to others. Then everyone on here wants to jump on the “you can’t ground an adult” bandwagon. She’s not an adult or even a remotely mature woman. She’s just a selfish ass.. *jumps off soapbox *. Sister needs to move now.

Lazy_Lobster159 − NTA. Unfortunately, Mia is one of those people (she may mature out of it) for whom rules are annoyances until there is a consequence that really stings. And then they cry victim. You have opened your home to her. All she should say is “thank you”. If Daddy thinks Mia is being treated unfairly he can welcome her back into his home and help her get her b**t to her early class.

This mom’s curfew saga shows how fast family generosity can fray when boundaries blur. By setting a hard line, she shielded her baby’s sleep but sparked a feud that split her family. It’s a reminder that even good intentions need clear rules to thrive. If you were in her shoes, would you ground your sibling or try another tack? Share your thoughts—let’s untangle this household knot together!

Share this post

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *