They’re horny horny hippos!

Fiona, the Cincinnati Zoo’s famous female hippopotamus, has been mating with the male that fathered her younger brother, according to a new report.

But unlike the incestuous Targeryan clan in HBO’s “House of the Dragon,” the unusual family dynamic isn’t nearly as cringey as it seems — because neither creature can appreciate the concepts of stepchildren and baby daddies, zoo spokeswoman Michelle Curley told Cincinnati TV station WCPO.

“Fiona and Tucker are not related,” Curley said. “This is totally normal for hippos.”

Fiona was born in 2017, six weeks’ premature and too small to stand and nurse from her mom, Bibi.

The calf — who weighed only 29 pounds, far below the normal birth range of 55 to 120 — became a social-media sensation after surviving with round-the-clock care from zoo workers who figured out how to recreate her mother’s milk and kept her warm in a makeshift hippo neonatal intensive care unit.

Fiona has since been immortalized through a slew of merchandise that includes T-shirts, calendars, mugs, plates, plush toys, children’s books, ceramic figurines, garden statues and Christmas ornaments.

Her dad, Henry, died later in 2017 at 36 and was replaced in September by Tucker, then 18, who was described at the time as Bibi’s “huge, dark and handsome” new boyfriend.

The couple quickly hit it off and Bibi gave birth to baby Fritz on August 3, after which the zoo released a captivating video of Fiona meeting her brother in a watery habitat dubbed “Hippo Cove.”

The hanky panky between Fiona and Tucker isn’t expected to grow the size of their hippo family — known as a “bloat” — because Fiona is on birth control medication, according to the zoo.

But so was Bibi when she got pregnant with Fritz, leading the zoo to say that “nature found a way and ignored our calendar” while announcing his birth.