This child is born, and society needs to give this child the best chance to break the cycle.
Kimi, I admire you for being the 'one that got away' - it takes a lot to break out of a perpetuating cycle. But that should make you even more understanding of how these children can get in that state.
I am amazed that anyone, in 2009, could honestly say that their 15 year old would not come home with their baby, whichever way it happened.
I used to do care work in a home when I was 19, and we had a lady who was there because she had been locked away in a mental institution for having a child out of wedlock. She was nonverbal, but when she saw a baby, at the age of 94, she shuddered and couldn't even touch it. She was so deeply traumatised.
The issue here is that you have two very young children who are being exploited for a good story, while there is a little baby in the middle, totally ignorant.
IF he is the father, then they both need support to be the best they can be for that little girl. Give them a chance to change all of their futures.