I heard about it in a course at uni. My lecturer knew of a woman who adopted twins from overseas. She had no intention of breastfeeding them but was being sent pictures of the mother when she was pregnant and pictures of the boys from when they were first born until when she got them (a few months later I think) and she found that she just started producing breast milk and was able to breastfeed both of them when she got them.
Isn't the mind and body just amazing!!!!