A colleague of mine (“J”), who lost her identical twin to cancer about four years ago, shared some interesting insights after she attended a sibling grief group. She has participated in several twinless-twin groups for many years. As a professional interested in learning more about her loss, she became curious about how nontwin siblings experience and manage their grief.

An important backstory is that J and her sister, like many other twin pairs, grew up without adequate maternal attention. J described that she and her sister acted as surrogate parents for each other. She was the caretaking twin who dedicated herself to her sister’s emotional and physical well-being from the beginning to the end of her twin’s ongoing medical challenges, which stretched more than twenty-five years.

Even before her sister passed away, my colleague recognized that she would need to find a therapist to help her prepare for and cope with her twin’s death as well as address how the loss of her sister would impact her fragile identity. She knew living without her twin was imminent. Nevertheless, through force of habit, her waking thoughts and life decisions were inextricably tied to her relationship with her twin.

J related that the sibling loss group highlighted a few major differences from her twinless-twin experiences. First, she was surprised by how nontwin siblings in the grief group were involved with others, including parents and other siblings. She explained that her twin loss experiences underscored how often twins are distant from their parents and other family members. In fact, she told me that despite innate and apparent differences, very little literature exists on how twin loss differs from sibling loss. Many twin families are confused and angry in times of loss because they don’t understand the complexity and interdependency of the twinship.

J related that it felt very unusual to hear siblings talk about their own grief as well as their parents’ grief—a subject that does not come up frequently in twinless-twin groups. She called the sibling survivors “forgotten mourners,” a descriptive term so very distinct from twin grief. Calling attention to some significant differences between twin siblings and nontwin siblings adds an important dimension in our ongoing quest to help twins and their families manage loss and grief.