My Adult Sister Blows up Only with Me and Our Mom

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Reader’s Question

Ever since we were kids, my older sister has had a temper. She’s almost 35 now and she still is quick to anger. As just one of many examples, once I didn’t receive a text message telling me to go feed her cat (basically the only reason she contacts me is to feed her cat). She called me up and started yelling at me. I explained that I didn’t receive the message, but I could still take care of it. She got all huffy and said it was fine and not to bother; she’d do it herself.

My sister is only like this with me and my mom — her husband called her out for controlling us and bossing us around. Even if we ask her to explain something, she’ll snap, say that she already told us, and get mad. A few years ago she mentioned being on Prozac, but I don’t think she is still on it.

Since she is always like this and has always been, is it just part of her personality? I don’t know how to handle her because I feel like I always have to walk on eggshells, and it makes me upset when she yells.

Psychologist’s Reply

Certainly, some people are quicker to anger or frustration than others. When considering whether such differences are due to how people vary in their temperament (personality), one important factor is whether the person seems to have always been out of the ordinary in this regard. One theory to explain differences in aggression across people relates to the fact that we all vary in the extent to which the neurotransmitter serotonin exerts its effects to lessen anger and increase frustration tolerance. Medications such as Prozac increase the effects of serotonin, and one of the beneficial effects of those medications is a decrease in anger and irritability.

Apart from the ‘why’ behind your sister’s anger, other important factors seem to be the ‘when’ and ‘who.’ You noted that she doesn’t treat everyone as poorly as she does you and your mother. If she did, she’d likely have no friends and no husband. When it comes to family, however, we often feel compelled to put up with mistreatment because we don’t want to cause further problems, or damage the relationship. The old adage that “blood is thicker than water” implies that we should remain bound to family, no matter what. Your sister seems well aware that she can vent her indignation toward you and your mother without any negative repercussions. So, we really shouldn’t expect her to change as long as that remains the case.

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Now that you’re all adults, it may be time to re-evaluate the nature of your relationships with each other. Questions to ask yourself include whether you would allow anyone else to treat you this way. You mentioned feeling uncomfortable with conflict. What might happen if you refused to interact with your sister when she did not treat you with the same basic respect she’d afford a friend or co-worker? Asking such questions often reveals the underlying dynamic that perpetuates the unhealthy relationship. For example, if conflict is more uncomfortable for you than for her, she may be taking advantage of that difference. If you imagine that your sister would eliminate the tenuous connection the two of you now have should you ever insist on being treated nicely, and you couldn’t bear the feelings that might arise if that happened, then your sister holds the power in your lopsided relationship.

If you do decide to alter the terms of your relationship, just be prepared that your sister is liable to try to bully you into the old arrangement. That is, she is motivated to keep things the way they are, so any attempt to change the dynamic will likely be met with resistance. Plus, talk is cheap. Only when she realizes that you have genuinely changed your behavior in the relationship will she possibly change hers. There is no guarantee that she will, but if she does not change, then that alone tells you something important about how she views her relationship with you, the needs that it meets, and what a healthier relationship between the two of you is worth to her.

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