It has been a strange couple of weeks in the politics of Northern Ireland. In a striking coincidence, the leaders of both major parties have come forward with revelations about their families that have raised questions about their own conduct.

It started before Christmas when Sinn Féin Gerry Adams revealed that he believed his father and brother had abused members of his family. Initial sympathy soon turned to tough questions about whether he had taken enough action in the light of this belief.

Adams' harshest critic has been journalist Suzanne Breen, who charged on Tuesday that other party leaders, such as the DUP First Minister Peter Robinson would have been forced to resign in his position.

Ironically, that could yet happen after the traumatic events of this week. On Wednesday, Robinson's  wife Iris, the MP for Strangford, disclosed that she had had an affair and had attempted suicide.

As in Adams' case, sympathy for Peter Robinson's clearly heartfelt statement soon gave way to renewed scrutiny. This time it came in the form of a BBC Spotlight documentary that examined the Robinson's financial affairs.

The programme alleged that Iris Robinson had helped her lover to establish a business as a tenant of Castlereagh Borough Council, where she is a councillor, and had solicited £50,000 for the project from two property developers, from which she took £5,000.

Iris Robinson has already announced she is stepping down from politics. The key questions now concern Peter Robinson's actions. The BBC reports that he attempted to get the money paid back, but that "he did not tell the proper authorities what he knew about the transaction despite being obliged by the ministerial code to act in the public interest at all times." There may now also be a wider scrutiny of the role of developers in Castlereagh, long regarded as something of a Robinson family fiefdom.

If the First Minister is forced to resign, the implications for devolution are troubling. His most likely successor, Nigel Dodds is regarded as something of a hardliner, and any attempt to elect a new First Minister could bring the long-running stand-off over policing and justice to a head.

If the executive were to collapse and precipitate an election, a three-way split within unionism could see Sinn Féin emerging as the largest party, in spite of Gerry Adams' troubles. That would leave Martin McGuinness, now perhaps the strongest politician in Northern Ireland, as First Minister-elect.

Given the likely reaction of unionism, that might well mean a return to direct rule from Westminster at a time when most calculate a Conservative Government is round the corner.

There are thus powerful reasons for both the DUP and Sinn Féin to contain the fall-out from their leaders' problems, but the next few weeks are likely to be a particularly febrile time.