But decades later, long after Diarmuid had flown the family nest for Mother Church, his older bother Seamus discovered that his brother's seminary training and career in the Vatican's diplomatic service had changed his personality dramatically: he was now more considerate of other people's feelings.
That the Archbishop of Dublin has learned "to sugar the pill" in personal relationships and formal communications is not in doubt in his major thunderbolt address, which he delivered on Monday evening to the devoutly conservative Knights of Columbanus.
His 4,000-word address was filled with the holy indignation of an Old Testament prophet. Yet there was no display of tantrum, no angry finger-pointing, nor name-calling of those whom he ranked among "strong forces which would prefer that the truth (of clerical child abuse) did not emerge".
Without throwing a public wobbly Archbishop Martin, however, indirectly identified as being among the "strong forces" of reaction Pope Benedict XVI, and the all-powerful Vatican Curia; and on the home-front, Cardinal Sean Brady and 'the Brady Bunch' in the Irish hierarchy, some of whom do not apply "with the rigour required" regulations and norms of diocesan child protection.
The archbishop included in his fisherman's net the priests, members of the laity and commentators who have denied the extent of the paedophile culture highlighted by the Murphy Report as being integral to a clericalist church culture that placed its power and prestige above the well-being of innocent children.
Alas, as is often his practice immediately after making headlines with a broadside verbal blitzkrieg, Archbishop Martin was unavailable yesterday to journalists who wanted to know what exactly he was saying and to whom was he specifically referring in his omnibus critique of collective denial of both clerical child abuse and an accompanying crisis of faith in a secularised society.
An official interpretation being put out on the Archbishop's behalf yesterday was that he had been asked to address the knights -- once the zealous vanguard of puritanism and piety at the height of the hierarchy's awesome power in the mid-20th Century -- on "the future of the Catholic Church in Ireland".
So this became the occasion for a comprehensive survey of what caused the heinous sins of the past within the sacred ecclesial portals; the remedial measures to be taken to restore the church's integrity and, above all, the vocation of all Catholics professing true Christianity to discover that "being church" was to follow the message of Jesus Christ.
This apologia, however laudable, overlooks the diplomatic messages alerting the public to power blockages inside Rome and Maynooth that result in the drip-feeding of more recent post-Murphy church failures to enforce proper protection of children against paedophile clerics.
In raising more questions than he gives answers to, Archbishop Martin will have ruffled robes among his Roman superiors and his fellow bishops; but his veiled allusions have won him the gratitude of victims who feared that their voices were once again being marginalised -- and discounted -- only six months after the publication of the Murphy Report into the Archdiocese of Dublin and a year after the Ryan Report on systematic abuse of children in residential institutions run by the religious orders.
At risk of being over-looked in the analytical quest for the source of Archbishop Martin's non-tantrum is the presence of two other powerful human emotions in his finely worded text.
These are the words of a man who feels badly let down and who, in turn, feels badly hurt -- wounded even.
To understand Archbishop Martin's cry from the heart, it should be recalled that after three decades away from the church scene here while working in the Vatican, he was sent in 2003 by the late Pope John Paul II as Archbishop-in-Waiting to Cardinal Desmond Connell -- whom he succeeded in 2004.
Archbishop Martin's special mission was to clean-up the Irish church of "clerical filth".
He adopted an open policy of full co-operation with the Murphy investigation, even in spite of attempted legal obstruction by Cardinal Connell.
The Murphy Report demands a radical response from the church hierarchy and the Government.
Is the knights' address a calculated move by a stalled archbishop to rally his flock to the wiles of the Pope and bishops?
Or is it the last farewell of an archbishop who has lost faith in their avowals of reform?
SIC: II