Throughout Gerry Adams' time as the public face both of Sinn Fein and the IRA, his family has been largely off-limits – until now.
A series of revelations about child sexual abuse involving his father and one of his brothers have caused huge shock both within the party he heads, Sinn Fein, and throughout Ireland.
Mr Adams has said that his father abused more than one member of his family, and that his brother Liam had abused his daughter.
Having admitted that he knew of abuses for years, he is facing searching questions on whether he did enough to prevent a recurrence. The detailed explanations he has already advanced about his conduct are being subjected to the closest scrutiny.
He has, of course, an array of enemies who would delight if the affair were to bring him down and damage Sinn Fein. At the same time, many supporters of the peace process, in which he played a pivotal part, hope it will not be seriously affected by the disclosures.
Mr Adams, 61, has been president of Sinn Fein for almost a quarter of a century. He has always denied being a member of the IRA, an assertion few take seriously.
His father, also named Gerry, was an IRA member in an earlier generation, while Mr Adams has a number of brothers and other relatives who have been highly militant republicans.
The family, based in west Belfast, have such a strong pedigree that they have been referred to as "republican aristocrats".
The present sequence of events began with one of the brothers, Liam, who in the 1970s was an IRA commanding officer in the Maze prison: Gerry Adams, in one of his books, described him as "highly respected".
Last Friday his daughter, Aine Tyrell, appeared on a Belfast television programme saying Liam had abused her since the age of four. It emerged that he is wanted by police in Belfast in connection with a total of 23 charges of rape and abuse.
Liam Adams has gone missing. After the programme Gerry Adams appealed to him to give himself up, adding that if he knew his whereabouts he would tell police.
Aine Tyrell said that in 1987 she told her mother, Sally, that her father had abused her over a 15-year period. Gerry Adams is then said to have driven Aine and her mother to confront Liam Adams, who denied everything.
Gerry Adams said that as soon as his family heard of the abuse a member of the family accompanied Aine and Sally to the social services, and Sally had taken Aine to the police.
A key aspect of this affair is that Liam Adams went on to work with youth groups both in Belfast and the Irish Republic. So far there are no reports that he was involved in any abuse in these, but the question arises of whether the Sinn Fein president could and should have prevented his involvement with young people.
According to Gerry Adams, he took steps to warn youth centres that allegations had been made against his brother. The organisation where Liam Adams had worked in the Republic said however that "at no point did we receive any information regarding what has come to light".
Gerry Adams responded sharply to allegations that he had promoted his brother as a Sinn Fein candidate. He declared: "Nothing could be further from the truth." He said that when he heard that Liam might be chosen as a Sinn Fein candidate, "I got that stopped and I got him dumped out of the party."
He continued: "When I discovered in the Belfast situation that he was working in a youth facility I went to those who had responsibility for that facility and told them of the allegation. He also had police clearance to work in those facilities. I also pressed Liam to come out of it and in the second case he did what I demanded of him."
Mr Adams insisted that he had said to many people, including Aine, that he would go public with them or go to the police with them if they wished.
A major complicating factor in this saga is Sinn Fein's attitude towards policing. In the 1980s going to the police would have been an amazing development, given that the IRA was still attacking and killing police officers. Today, however, Sinn Fein accepts and supports the much-reformed police service, so that Gerry Adams now feels free to ask his brother to go to the police. Yesterday he said: "If he feels isolated or feels that he cannot do this, we will go and get him and bring him to the police."
The Sinn Fein president added: "I wouldn't say that I handled this perfectly – of course I wouldn't. But I tried to do my best by Aine and I tried to do my best by others within my family and, as far as I could, we tried to ensure that no other child was at risk."
The next development came at the weekend when the republican leader explained that he later discovered that his father, also called Gerry, had abused members of his family, in which there were 10 children.
His father had carried out abuse, he said – "It was physical, it was psychological, it was emotional and it was sexual." He would not say how many family members had been involved, or whether Liam Adams was among them.
He said he had confronted his father, who remained in denial for a long time. The family had established, he said, that his father's activities were "historical crimes".
He said that from then on the family ensured that no child was ever left along with his father, who was in any case "increasingly disabled, incapacitated and elderly". His father, who died six years ago, "ended up dying a very, very lonely old man".
Adams Snr was buried with full republican honours, his coffin draped with an Irish tricolour flag. His son said yesterday: "Personally that was one of the great dilemmas for me. I didn't want him buried with a tricolour. I think he besmirched it."
The early signs in west Belfast, which Gerry Adams has long represented at Westminster, are that the episode has come as a huge shock, but that anger and blame is being directed at Gerry Snr and Liam rather than the MP.
Child sexual abuse has of late been one of the most scalding issues in nationalist Ireland, with a Catholic bishop resigning last week following a searing report on the church's "inexcusable" handling of complaints against priests.
The shock of the Adams affair has been so severe, however, that it will take some time to assess what damage has been done to Sinn Fein and its leader. He is adamant that there was no element of cover-up in his behaviour over the years.
Much will depend on what if any further revelations lie ahead, and on the final communal judgement on whether Gerry Adams did everything he could, especially in relation to his brother Liam.
He has in the last few years stepped back somewhat from the political front line, with Martin McGuinness coming much more to the fore as Deputy First Minister in the Belfast devolved administration.
Sinn Fein will be anxiously hoping that the damage from the episode can be kept to a minimum and that the personal problems of the Adams family can be contained rather than developing into a political crisis.
Support for the party has risen steadily for more than a decade to the point where observers believe that there is a chance, in the next couple of years, of it becoming the largest political party in Northern Ireland.