It’s not known who Bert’s father was. It could not have been Thomas Fonner, for he died in 1865. He may have been George Weymer, but he “abandoned” Bert’s mother in June 1867. Or, it could be another person.

1900 Census, Morris Twp., Greene Co., PA928
Fonner, Bert, 29, b. PA, Jul. 1870
Ziza, 23, b. PA, Jan. 1877
Floyd, son
George, son