If Rozella was adopted by Mr. Kern, she can request a copy of her original birth certificate. Go to www.newillinoisadoptionlaw.com/
for more info.
If she wasn't adopted, you can contact the Clark County Clerk & Recorder Deeds for a copy of her birth certificate. They have birth and death records starting in 1865.
However her father's name might not be on her birth certificate. You might have to take a DNA test. I don't know much about it but the DNA Detectives, www.thednadetectives.com
explains how it works. Successful Searching!