The phrase "biological father" refers to the man who provides half of a person's genetic makeup and is responsible for their conception. He is the person's natural or physical father, as opposed to an adoptive or stepfather. Full definition
This is typically done through genetic testing to confirm that the father is the natural and biological father of the child. (dewittlaw.com)
Every state has certain laws that address the issues related to biological fathers in adoption. (beaconhouseadoption.com)
However, it does not list other exceptions or appear to propose consequences for biological fathers who refuse to participate in formally acknowledging paternity or make themselves available for DNA testing. (thespruce.com)