Under Illinois law, paternity is a term that refers to the biological relationship between a father and his child. This relationship also has legal implications. Paternity is used to determine matters such as child support, custody, visitation and inheritance.
Determining a child's paternity may be necessary when matters of child support, child custody or adoption are involved, and DNA testing is used to examine DNA markers and look at the relationship between two people. When Illinois residents undergo DNA testing, samples from a mother, child and alleged father are taken. These tests have a 99 percent certainty rate or higher.