The Clancy Brothers were an influential Irish folk group, which initially developed as a part of the American folk music revival. Most popular in the 1960s, they were famed for their trademark Aran jumpers and are widely credited with popularising Irish traditional music in the United States and revitalising it in Ireland, paving the way for an Irish folk boom with groups like the Dubliners and the Wolfe Tones. The Clancy Brothers, Patrick "Paddy" Clancy, Tom Clancy, and Liam Clancy, are best known for their work with Tommy Makem, recording almost two dozen albums together as The Clancy Brothers and Tommy Makem. Makem left in 1969, the first of many changes in the group's membership.

In 1988, the Clancy Brothers (Paddy, Tom, and Bobby) with Robbie O'Connell recorded a poorly mixed live album at St. Anselm College in Goffstown, New Hampshire, Tunes 'n' Tales of Ireland. Bobby Clancy called this album "crap", and Paddy referred to it as "not our best effort". Regardless, the album is notable as Tom Clancy's final record. In May 1990, Tom Clancy was diagnosed with stomach cancer. When he had surgery later in the summer, Liam filled in for him during the Clancy Brothers and Robbie O'Connell's August tour. The surgery proved unsuccessful, and Tom Clancy died at the age of 66 on 7 November 1990. He left behind a wife, a son, and five daughters. His youngest daughter was only two years old at the time. With the death of Tom Clancy, Liam again stepped in full-time with his brothers. This line-up experienced a more active schedule than the group had during the previous decade, with appearances on Regis and Kathie Lee in 1991, 1993 and 1995, a performance at the 30th Anniversary Bob Dylan concert at Madison Square Garden in 1992, seen by 20,000 live and 200 million people worldwide on television, and the formation of Irish Festival Cruises in 1991, an annual cruise of the Caribbean with live folk music. They also brought their own tour groups to Ireland, which Robbie O'Connell continues to do to this day. The Bob Dylan concert inspired the recording of the first studio album by the Clancy Brothers in over twenty years, since 1973's Greatest Hits. Released in late 1995, Older But No Wiser introduced all newly recorded songs with the exception of "When the Ship Comes In", which the group performed at the Dylan concert. It was the only recording to feature the line-up of Paddy, Bobby, Liam Clancy, and Robbie O'Connell. Older But No Wiser was the Clancy Brothers' final album. The Irish Festival Cruises had led to financial disputes between Paddy and Liam. Liam decided to leave the group because of this. Robbie O'Connell, now with the group for nineteen years, was ready for a change as well. The two left the Clancy Brothers together and formed their own duo, simply called Liam Clancy and Robbie O'Connell. Before splitting up, the Clancy brothers and Robbie O'Connell gave a Farewell Tour of Ireland and America in February and March 1996. One performance in Clonmel as part of their Irish tour was televised and later released on video and DVD as The Clancy Brothers and Robbie O'Connell: Farewell to Ireland. On the album Older But No Wiser and the concert video Farewell to Ireland, respectively, two sons of Clancy brothers made their recording debuts. Donal Clancy, Liam's youngest son, played backup on the studio album, while Bobby's son Finbarr Clancy performed with the group on the filmed Farewell concert. Bobby was not well at this time and Finbarr was brought on, in part, to aid his father for this concert. He had first performed with the group the previous year as a replacement for his father when he had heart surgery. Finbarr did not join them for the American tour. CANNOTANSWER

Answer the following question by taking a quote from the article: Who were his sons?

Donal Clancy, Liam's youngest son, played backup on the studio album, while Bobby's son Finbarr Clancy performed with the group on the filmed Farewell concert.