It is a twin thing. It is that unmistakable bond that begins in utero. So when Allison Ardolino Dinkelacker couldn't conceive but wanted to grow her family, her identical twin sister, Dawn Ardolino Policastro, offered her womb. And on Aug. 5, Hudson William Dinkelacker was born. A picture taken by a professional photographer shows their playful photo caption: "Her bun (Allison), Her oven (Dawn)."

When Allison was 30 weeks pregnant with her first child in 2009, she was diagnosed with stage-3 breast cancer. An emergency caesarean section was planned at 31 weeks, and her son Dylan was born. Allison went through chemotherapy immediately following.

Fast forward six years. A cancer-free Allison desperately wanted another child. During a visit to her oncologist, it was determined that the cancer, brought on by hormones, would make it impossible to carry a child, even if Allison were to get pregnant. Accompanied to the appointment was twin Dawn, who immediately said "no worries." "It doesn't matter because I am going to carry their child,'" Allison wrote on her Facebook page, according to Fox News.

A beautiful picture of the twins during Dawn's pregnancy was taken by a professional photographer. This picture went viral and as of Wednesday afternoon had more than 80,000 likes, according to USA Today.

"How can we ever begin to thank you for your tremendous generosity and sacrifice you so willingly bestowed these last few months?" Allison wrote on her sister's Facebook page, according to Parenting Magazine. The 37-year old twins live just three blocks away from each other, in Mineola, N.Y. Their bond today is even stronger.