My sister and I didn't speak for decades. Can a baby change that?

The woman at the vegan restaurant mentioned her thumbs. They looked like they had been crushed, just like mine. I felt the rush of connection, followed by the pain of regret. This woman, my sister, was a stranger.

We last saw each other over thirty years ago. I was 7; she was 29. We were burying our father.

During the many years in between, I often wondered why she disappeared. Was a sister so unnecessary? My grief and resentment had calcified into something internal and essential, like bone. The prospect of reconciliation that had once sustained me was long gone. Yet here she was, in Chicago to meet my newborn baby.

Alcoholism had ravaged our extended family and spared no one. Even those who weren't addicted suffered from its vagaries. She married an alcoholic. I became one. But without knowing it, we began parallel recovery journeys in twelve-step meetings. She found a lens to understand the erratic behavior of family members who were bubbly but sometimes cruel. I began to see myself and my own imperfections more clearly, and realized that I didn't need an apology to forgive her.

The disease tore us apart, but maybe recovery can bring us back together after the birth of my first child. In our family there was a history of longstanding resentment between siblings. It felt like an inheritance that I didn't want to give to my daughter.

My sister and I came from a colorful but complicated clan full of people who were both witty and sharp-tongued. Our grandmother, a newspaper columnist, was a notorious drunk among the country club crowd of small-town Maryland. Three of her four children suffered from their own addictions.

Our father, also a journalist, escaped the clutches of alcoholism but possessed the same manic energy that drove so many members of his immediate family to drink. His untimely death in a fiery single-car accident left a void that we all tried to fill in different ways.

My sister had been through enough drama and left the family tableau. And an unrelenting distrust developed between my older half-siblings and my mother, an overwhelmed young widow with two little girls. I became a chronic worrier and a compulsive overachiever. The collapse of my family as I knew it left a hole that I spent my adolescence looking for drugs and alcohol to fill.

For years, the losses felt too overwhelming to even explore in therapy. But during my recovery, I started to come to terms with it. At the same time I became more open and less critical. Veterans at the recovery program I attended told me that I couldn't stay angry at my sister for the choice she made, that resentment was fatal to people like us.

Psychologists call estrangement from siblings an ambiguous loss. Unlike death, where the farewell is final, the sister or brother left behind mourns without ever finding a solution. This is what it felt like to me: a pain that dulled over time, but never fully healed.

although one in four Americans experience alienation, there is little research on the rifts between siblings. The impact can be profound and long-lasting, according to Fern Schumer Chapman, the author of several books on the subject.

“This is someone who you thought should be part of your life experience who has chosen to reject you,” said Mrs. Schumer Chapman, who was estranged from her brother for 40 years. “And they still walk the earth.”

“How often have you thought about me?” Mrs. Schumer Chapman said she asked her brother after they reconciled. “He said, 'Every day.' And I really wasn't prepared for that.”

Recently one large longitudinal study in Germany found that alienation “can have potentially far-reaching consequences for family functioning and the well-being of individuals.” The same study found that estrangement between siblings was not uncommon, “but often only temporary.”

And so it seemed like it might be for my sister and me: a 32-year blip.

For all the distance that alcoholism caused in our family, there was also a pattern of change. One aunt got sober, then two cousins, then my younger sister and a second cousin, then me.

So in May, I shared my baby news with my older sister via a Facebook message, the first message we had exchanged in years.

“I just wanted to let you know that you have a new niece!” I wrote and sent a stream of photos.

She quickly wrote back and suggested a visit.

I was receptive to it, but as the reunion approached, my insides began to churn. I was afraid I was in for another disappointment.

My father's early death and my mother's resulting marital status—single, widowed—felt like a mark in the hallways of my parochial school in small-town Illinois. I often fantasized about my big sister's return as a miracle cure for my isolation and loneliness.

But as the years passed and I went through the pain of adolescence and early adulthood without her, I let go of that possibility. I learned to arm myself against the wave of sadness that still sometimes came over me.

I wore that steely armor when I pushed a stroller into the Chicago Diner in July. There my sister sat in a booth with her son – a 23-year-old nephew I was meeting for the first time. The conversation, mainly about his first impressions of Chicago, was stilted at first. Then my sister noticed my thumbs. Just like hers.

After lunch we walked a few blocks to the brownstone where my younger sister and I spent our early childhood years. The sight of the building always brought back memories of my older sister sitting on the hardwood floor with me to play with Fisher-Price toys and calling me “Stinky,” a nickname I found hilarious as a toddler. Those memories came flooding back when I stood on the sidewalk with my three-month-old daughter, my long-lost sister and her son.

After our summer reunion, our relationship continued to grow. In the fall we had another visit and several long phone conversations.

“I unknowingly did a lot of the things they did,” my sister said recently about our family, when I summoned the courage to ask her why she left. “I didn't know how to resolve a conflict,” she added. “I guess I thought you just disappeared.”

I struggled to let go of the feeling of abandonment that had so indelibly shaped me. It helped that my identity had changed: I was now a woman writing her own story, and a mother caring for a small baby. My siblings and I were all a little broken; Maybe coming together around my daughter would make us more complete.