The son appears to be taking revenge. Revenge for his father, the man current German leader Angela Merkel succeeded as chancellor after Germany's interlude with the Social Democrats under Gerhard Schröder. And taking revenge, too, for his mother's tragic suicide.

It's a personal and political drama that Kohl's son, 53-year-old Walter, brought back to the fore with a long interview with "ZEITmagazin." He repeated accusations against the Christian Democratic Union (CDU), the party of Kohl and Merkel, and against his father's new family. He also leveled some very harsh new accusations at Merkel and her rise to the top of German politics.

"Shabby. For me, Frau Merkel played a not insignificant part in my mother's death. I have to put it that drastically."

It's a statement that hits the current chancellor and CDU party leader personally and which could also have consequences for her political future with German elections set for September and the SPD experiencing a budding revival.

How did it come to this?

Tuesday, January 18, 2000: Helmut Kohl resigns as honorary chairman of "his" CDU. First, he lost the 1998 election, then he was implicated in a political scandal involving secret donations to a CDU slush fund.

A few weeks earlier, Angela Merkel, then the party's general secretary, publicly distanced herself from Kohl, her political mentor, in an article published by the "Frankfurter Allgemeine Zeitung." She wrote that the time had come for the CDU to separate itself from Kohl, whose role in the slush fund scandal damaged not only his own credibility but that of the entire CDU.

The political had become personal. Hannelore Kohl died the following year, an event her son Walter commented on this way:

"Neither then nor at any subsequent time did Frau Merkel did say publicly: Leave the family out of it. She knew very well, though, that my mother was seriously ill."

To understand Walter's condemnation of Merkel, it's crucial to understand how he and his brother, Peter, suffered as a consequence of their father's political career. Nowadays it's hard to comprehend just what a force the former chancellor was. His weighty, 1.93-meter (6-foot, 4-inch) frame was a presence to be reckoned with at the parliament in Bonn - it was clear then that this was a man set to determine his own future.

It is clear now that he did it, partly, at the expense of his own family.

The plot thickens

For many years, Kohl's first wife, Hannelore, and his two sons presented an idealized image of a model family. But behind the scenes, things were very different. Years later, Walter Kohl opened up and described the traumatic experiences he had as a child in his books, which flew off the shelves, and on talk shows watched by millions.

"When I was 11 or 12 I was repeatedly beaten up by older school kids because the slogan was: Punch Kohl in the face! They couldn't get at my father, but they could get at me. When political discussions would get heated, I'd know: here we go again. Older pupils often waited for me in the toilets; one would stand with his back against the door while the others beat me up and shoved my head in the urinal."

These are not the sort of things you forget.

Political scandal, personal tragedy

Hannelore Kohl later developed a severe allergy to light and eventually could only leave her home after sundown. From what we now know, the former chancellor's wife must have suffered terrible pain. On July 5, 2001, at the age of 68, she took an overdose of sleeping pills while at home in Ludwigshafen-Oggersheim. Her husband was in Berlin at the time. Passages from her farewell letter were later published, with his consent. "You must keep going," she had told him. "I love you and admire your strength."

Helmut Kohl, now 86 years old and wheelchair-bound, still has many admirers in the CDU. They prefer to forget that in 1998 Kohl's CDU-FDP coalition suffered a crushing defeat. One year later, during the slush-fund scandal, Angela Merkel seized the opportunity to take power.

Asked what happened to his mother at that time, Walter Kohl replied:

"My mother was vilified in the most appalling way, even being called a donations whore. She was accused of all kinds of things. She lost face. She became a non-person. It was all the more painful for her because she felt betrayed by Angela Merkel. They had once been very good friends."

Who is hurting the CDU now?

This week's interview with Kohl's son appeared at a time when many in the CDU are nervous. The refugee crisis and Chancellor Merkel's methods for dealing with it have created a lot of resistance. That's provided Walter Kohl with the opportunity to turn a personal feud into a political critique.

"I think the CDU today is a party with no clear outline. It's everywhere and nowhere. At the same time, they're deploying vocabulary like 'brand essence' - it sends shivers down my spine. Sorry, but we're not talking about soap or soft drinks; we're talking about people and organizations that determine the fate of our country."

It's his attack on Merkel as the leader of both Germany and the CDU. The former-chancellor's son, who now works as a businessman, speaker and consultant, expressed his distaste for both the CDU and the far-right Alternative for Germany (AfD). In his interview, he added that current politicians' policies are partly to blame for the AfD's popularity.

 "A party like the AfD would not have come to prominence if so-called established politics had acted differently," he said.

Could there still be another political reckoning yet to come? Walter Kohl's comments on soap and soft drinks won't go unnoticed in the CDU, and many are likely to agree with his assessments of both the CDU and the AfD. His father, seen as the "Reunification Chancellor," is probably one of them.