There is a website for births if the mother was willing to make the information public from the state of Iowa. OR you can go to the court house in Denison to the County Recorders office - but he would have to do that with his driver's license and ask for his birth record to see if it's listed on the birth record. The State of Iowa - Lucas Building - also has that information but they charge $20 and he still would have to send a photocopy of his driver's license and complete their online form with his money.
Hope that helps.