Robert was born 13 Dec 1920 according to the Social Security Death Index. I couldn't find him in the 1930 US Census when he would have been about 6 years old and normally with his parents. A family member could order his death certificate which would name his parents. Family members are by US law allowed to obtain death records for any family member who deceased less than 70 years ago. A marriage license for them at Liege might also name his parents.