Can two sisters have bipolar?

My girlfriend has Bipolar one and her sister doesn't think she has it but has some signs of it. They both want to move in together but sometimes it's off and on all the time. They both get into yelling at each other over little things.

Thanks for the help.

Of course sisters can both have bipolar disorder. If the gene is strong in a family, there is a likelihood that many in the family can develop it. Unfortunately, that has been the case in my family. My paternal grandmother had a confirmed BP, my dad, I do, my sister, and my youngest nephew. I also have a 1st cousin with a BP dx. The severity and general characteristics/course/nature of our BP cases have varied a bit among us.

Others in my family have also had signs of possible bipolar disorder or at least depression and/or anxiety.

Yes, sisters can have bipolar. They have both inherited the gene. However, the presentation of bipolar behaviors is triggered by a very stressful or upsetting event. So, one sister may present with bipolar because she experienced a triggering event, and the other sister won’t present because she did not experience a triggering event.

Sure. I have BD and I have often wondered if my sister had it, too. I feel pretty sure she did. We had the same parents, but didn't grow up together (she was much older than I).

I wonder if there’s a difference with half siblings? It would make sense to me. I have two half brothers and one half sister. One from my moms second marriage and two from my dads. The BP runs strong on my dads side and I have it. My middle daughter does too. None of my siblings have any mental health disorders.

Sure. But they can also share a disfunctional coping skills from growing up. Or personality traits that make it challenging to live together. Don’t label her til she’s been diagnosed.

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Originally Posted by sarahsweets I wonder if there’s a difference with half siblings? It would make sense to me. I have two half brothers and one half sister. One from my moms second marriage and two from my dads. The BP runs strong on my dads side and I have it. My middle daughter does too. None of my siblings have any mental health disorders.

I think it would all depend upon which genes the person inherited.

I'm a twin and I worry she will develop bipolar at some point there is a high percentage if one twin has it the other will too plus we are identical

Yep 2 of 3's of my siblings have been dx'd the 3rd one is to afraid to get dx'd.

I think my sister has a bit of bipolar. I know she has depression and was on meds for awhile. My brother and I are both diagnosed autistic. My mom thinks my dad was on the spectrum as well.

Their father had bipolar and spend lots of money. Both sister's spend money big time and always buying clothes and vehicle's that they can't afford. The sister that doesn't take meds for the condition is real manic when driving on the highway.

This is why I didn’t have biological kids because I didn’t want to chance passing on my mental health issues. I know it is not a guarantee but why chance it.