‘My mother did the whipping, too. Flogging! Today you can’t discipline your child any more. If you spank him, they call it child abuse! What child abuse? What was my mother supposed to do with him?’

‘One day we are eating lunch. My father is sitting here,’ said Eleanor, gesturing to the top of the family dining table. ‘The phone rings. Someone answers it and says “Sir, there’s a Father so-and-so who wants to talk to you.”’ It turned out to be no less than the director of Ateneo de Davao High School himself.

‘“Governor,” he says, “would you happen to know where your son is? Rodrigo. Governor, I need to tell you that he hasn’t been at school for the past two months.”’ Eleanor’s voluminous attempt to mimic her father’s response was startling.

‘“WHAAAAAT?”’ she screeched. It had the feel of a practiced rendition of a family favourite; today this story features prominently in the presidential apocrypha.

The governor called his security chief, she said, a high-ranking officer in the Philippine Constabulary, and ordered him to go and find his son. They went to Davao police headquarters, but no one there knew anything.

‘They went all over the city,’ Eleanor said. ‘They asked all his friends. They don’t know.’

Presumably, at their suggestion, they went to every cock-fighting gallery and billiard hall. Still they couldn’t find him. The governor reckoned Rodrigo would be somewhere in the city, roving round, and ordered the police to make a public announcement in city cinemas.

‘So someone put a notice up and it said, Rodrigo, if you see this notice, your father says “Go home this minute.”Finally, he shows up. It’s already dark. My mother looks at him and says “You had better answer your father to his satisfaction or you will reeeeally, reeeeeeally be in trouble.” My mother is only good at making him kneel down.’

That night, the eldest son of the governor of Davao was sentenced to kneel on mung beans.

The spare room with the altar is on the right at the top of the stairs. Downstairs, in an extension of the original house, a private chapel was created for their mother, Soledad, better known as Nanay Soling, who died in 2012, aged 95. The chapel’s walls are festooned with Catholic iconography, electric candles, plastic sunflowers, and statuettes of angels, Jesus, and the Blessed Virgin. Dark-wood prayer-kneelers stand on an ersatz Persian rug, and, on the wall, above the candle-cluttered altar — crowded with yet more statuettes — a clunky mural has been painted. It features the Holy Book, opened to the Ten Commandments.

‘Honour thy father and they mother,’ it reads. ‘Thou shalt not kill. Thou shalt not commit adultery.’

Compared to such heinous crimes, Rodrigo’s boyhood misdemeanours really seem quite trivial. But, after catapult-gate and the black ink on white cassock affair, it seems Rodrigo’s prolonged absence from Ateneo de Davao High School was the straw that broke the camel’s back. In his own version of the story, he was expelled. It sounds better to tell it like that. What seems to have actually happened is that the school, wary of the fact that they were dealing with the governor’s son, begged his parents to find another school. Which, finally, they did.

‘My dad was the kind of person who would never want to be humiliated or embarrassed,’ said Jocelyn, the younger of the two Duterte sisters, three years Rodrigo’s junior. She remembers the fallout from the incident as though it happened yesterday, and reckons it must have been at least the third time the school had called to scold the governor.

‘I can remember my father turning red and going looking for him,’ she said. ‘He was the only one in the family who had a taste of my father’s temper. He tried to give my dad time to cool off. I used to like it when my dad was so angry at him. I never saw my dad that way.’

Jocelyn told me she was a daddy’s girl.

‘I remember he was so angry and was holding him by the neck and practically …’ She didn’t finish her sentence, but instead held out her rigid, shaking, strangling hands.

Jocelyn never referred to her brother by name, only as ‘the mayor’ or ‘the president’.

‘He became a very street-smart kid,’ she said. ‘The mayor was exposed to the street by his bodyguards. He had his police buddies and his bodyguards, and they looked after him. He’s very knowledgeable. You cannot fool him. He knows what’s happening.’

Jocelyn is bijou, slightly built, like her brother, and unmistakably his sister.

Human rights day.