if the facts are as you describe and imply - i.e., there was non-coercive sexual intercourse - the 25 year old could be prosecuted for Criminal Sexual Penetration fourth degree (once known as statutory rape).
I've seen several cases like this that were never prosecuted apparently because the people involved didn't complain, they just cared more about taking care of the baby than punishing the dad. But it's important for the mother to do do a paternity action, get the father legally on the hook for child support. The threat of prosecution could provide leverage to get cooperation from the father.
Parents could conceivably be liable for child neglect or abuse depending on their degree of negligence or involvement in the relationship with the guy. Not likely to happen. Again, somebody has to complain.
