Allison Ardolino Dinkelacker wanted to have a second baby, but a bout of breast cancer left her unable to conceive. Assisted reproductive technology was off the table: Her oncologist said even if she survived a pregnancy, she wouldn't be able to carry any other children. Lucky for Allison, her identical twin sister, Dawn, was ready to help, even going so far as to offer herself as a surrogate.

Wanting to grow her family, Allison agreed, and the sisters embarked on this most extraordinary adventure. It wasn't an easy road—is pregnancy ever a breeze?—but it seems to have brought the siblings even closer. "When most people would have given up during the struggles we endured, you just pushed through it all," Allison wrote on Facebook. "Time and time again when we thought we should quit, you never gave up. You don't believe in the words, 'I can't.' You only see 'I can,' and so many times YOU DID!"

On August 5, Dawn gave birth to her nephew, Hudson.

The sisters' heartwarming story has clearly struck a chord: After Hudson's birth, Allison Rose, a professional photographer, posted some shots she took during a photo session with the sisters. (One of them is pictured at the right.) They've since gone viral, racking up over 77,000 likes, 14,000 shares and lots of love from the Internet. Comments ranged from hopeful ("I'm a cancer survivor (bone cancer) of 3 years. My doctors told me I would never have children, I was devastated.. 2 years after cancer I was pregnant with my beautiful daughter that is now 2 months old") to grateful ("This has got to be the most amazing story of love, hope and faith... Thank you for sharing this journey with us all"). No word on how many people were brought to tears, but my guess is that I'm not the only one.

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Bonnie Gibbs Vengrow is a New York City-based writer and editor who traded in her Blackberry and Metro card for playdates and PB&J sandwiches—and the once-in-a-lifetime chance to watch her feisty, funny son grow up. Follow her on Twitter, Pinterest, and Google+.

Photo of Allison and Dawn courtesy of Allison Rose Photography via