I have a 17 year old daughter who has just recently met Scott (the man I've always believed was her father) for the first time. He has cystic fibrosis, so there is a question of his fertility. I'm a nurse, but have never worked in this field. My question is this: could he have fathered a child when he was 18 and then have become sterile years later, as the disease progressed? There is a possibility that he is not her father, as I did sleep with one other man while I was dating him. However, she resembles him, has features like him and is very smart and creative, as he is. Neither he nor my husband and I can afford to have DNA testing done at this time, but we would like to, for our peace of mind, as well as Scott's. Any ideas on the liklihood of him being her father?