The idea that suicide bombers are insane or religious fanatics is challenged by some controversial new research that has been reported over that last few days in a variety of publications, from 
Yale Global in the US to the Daily Star in Lebanon and the Daily Times in Pakistan.

The article is by Riaz Hassan, an emeritus professor at Flinders University in Australia which claims to hold the world's most comprehensive suicide terrorism database, covering 1,200 attacks between 1981 and 2006.

Hassan writes:

The evidence from the database largely discredits the common wisdom that the personality of suicide bombers and their religion are the principal cause. It shows that though religion can play a vital role in recruiting and motivating potential future suicide bombers, the driving force is not religion but a cocktail of motivations including politics, humiliation, revenge, retaliation and altruism. The configuration of these motivations is related to the specific circumstances of the political conflict behind the rise of suicide attacks in different countries.

The main motive for many suicide bombings in Israel, he says, "is revenge for acts committed by Israelis". Among Libyan volunteers in Iraq, the motive appeared to be not so much "global jihadi ideology" but "an explosive mix of desperation, pride, anger, sense of powerlessness, local tradition of resistance and religious fervour".
He continues:

Apart from one demographic attribute – that the majority of suicide bombers tend to be young males – the evidence has failed to find a stable set of demographic, psychological, socioeconomic and religious variables that can be causally linked to suicide bombers’ personality or socioeconomic origins. With the exception of a few cases, their life stories show no apparent connection between violent militant activity and personality disorders.

Typically, most suicide bombers are psychologically normal and are deeply integrated into social networks and emotionally attached to their national communities.