A photo of a mother breast-feeding her own son and her friend’s son has gone viral, resulting in controversy, WPVI reported.

Jessica Colletti, 27, of Bala Cynwyd, Pennsylvania, volunteered to nurse the son of her friend Charlie Interrante, 25, after Interrante discovered she was unable to do it herself. Interrante’s son, Mateo, reacted badly to formula.

"I was at my wits’ end, and when she offered, I was nothing but thankful for it," Interrante told ABC News.

Colletti had not nursed another woman’s child before this but told the news channel that it was very natural.

“My friend struggled with breast-feeding in the beginning and succeeded for nine months,” Colletti told the blog Mama Bean Parenting. “She was always very happy that her son had the nutrition and comfort he needed while she was working.  Being able to breast-feed her little boy has created a special bond between us all— a bond I will always cherish."

The photo was posted on Facebook on the Mama Bean Parenting blog’s page. Colletti’s son, who is 16 months old, is pictured on the right, while Mateo, who is 18 months old, is on the left. When asked whether she was concerned about how Mateo would react to seeing this photo when he gets older, Interrante said she didn’t think so.

“[Colletti] treats him like a son, and I think he’ll grow up and always look at her like that, and I’ll always be open about the relationship they have,” she told the news channel.

The image has sparked controversy, with some online commenters applauding the moms, but others criticizing their decision.

According to the World Health Organization (WHO), breast milk, including that expressed by a wet nurse, is the ideal food for healthy growth and development of infants.  When an infant cannot  be breastfed, the WHO recommends breast milk from a healthy wet nurse as a suitable alternative.

"Of course, there's a risk with anything you do that's not the biological mom's breast milk,” lactation consultant Kathleen McCue told ABC News, “but if the woman has been screened, if she's healthy, if she is substance free, if her child is healthy as well, it shouldn't be a problem.”