The daughter reported to police that she told her mother about three years ago that she wanted to meet her biological father.
Her mother arranged a meeting with Fieldgrove, and the young woman and Fieldgrove had a father-daughter relationship until September 2018 when it turned sexual.
Samantha Kershner and her father Travis Fieldgrove are charged with incest. Photos / Hall County Jail
The pair were then exposed by Kershner's mum, who contacted police and told them about the incestuous relationship.
The father and daughter admitted having a romantic and sexual relationship despite knowing that they were related, and got married.
The 21-year-old also told police that she wanted to have sex with Fieldgrove because she was in a "jealous competition with her half-sister regarding who could have sex with their father," according to a court affidavit.
Fieldgrove brazenly announced the illegal union on his Facebook page, even though DNA tests have confirmed their biological relationship, authorities said.
The other sibling has not been named or charged with any offence.