Presumption of Paternity: Contacted 26 Years Later About Child

My question involves paternity law for the State of: Illinois.

i have just recently been contacted by a young man that believes he is my biological son according to his mother. I was never placed on the birth Certificate at birth since i wasn't even aware of the child. My question is can the mother come back after me for child support 26 yrs later?

Presumption of Paternity: Contacted 26 Years Later About Child