While a sister may have genuine love for her other siblings, there can be underlying insecurities which mar the face of the relationship. According to a study conducted by the Health Department of Manitoba in Canada, jealousy among siblings can grow from sibling rivalry developed while growing up. Now that you are no longer children competing for the attention and affection of your parents, how can you tell if your sister is harboring jealousy? This can be difficult considering that sisters who are jealous are not always direct and may engage in passive-aggressive behavior.
Displays Feelings of Inadequacy
The insecurities that feed jealousy will oftentimes leave a sister feeling inadequate, as if she is of less importance than her siblings. This is worse if the sibling appears to be more successful socially or is in what is considered a more prestigious position. For example, the jealous sister who has a job as a sales rep may still express that her sibling, the lawyer, is better off, even if it is well known that she makes more than they do through commissions. She finds it difficult to be genuinely happy for the successes of her brothers and sisters.
Always Ready to Compete
Jealousy in your sister can mature as you get older. But even as adults, she may still be competing for the affection of your parents. You may find that your sister is overly competitive where you are concerned. She may try to be the first to marry or the one who bears the first grandchild. In an article for the Wall Street Journal, Elizabeth Bernstein interviewed a sister who actually named her first son Jack, the same name her sister had given to her own son a few weeks earlier. A jealous sister may push herself to try harder and be better than her sibling in as many aspects of their lives as possible.
Easily Agitated and Enraged
Jealousy can often be displayed as rage and anger. Temper tantrums are common with children but may not completely disappear in adulthood. A sister who harbors feelings of jealousy may often lash out and become aggressive toward her siblings, even when nothing was done to provoke such a strong reaction. She may make belittling remarks and insulting comments in an attempt to debase them so that she may in some way feel better about herself. This agitation may even extend to the friends or lovers of her siblings who may feel that she really doesn't like them at all.
Pulls Away and Becomes Withdrawn
On the other end of the spectrum, instead of acting out, jealousy can result in your sister being subdued and unresponsive when interacting with you. She may finally pull away from the sibling relationship or the entire family altogether. In avoiding family gatherings, she will not have to face up to any comparisons that may be made between her and her siblings or watch her siblings getting more attention, praise and affection than she is.