The Guardian today published a lengthy article about an MI5 report they had obtained (which was restricted), which stated that there was no real profile which could indicate what sort of young Muslim would get involved in terrorism. One important factor, though, was that a strong religious commitment meant one was less, rather than more, likely to get involved:
The majority are British nationals and the remainder, with a few exceptions, are here legally. Around half were born in the UK, with others migrating here later in life. Some of these fled traumatic experiences and oppressive regimes and claimed UK asylum, but more came to Britain to study or for family or economic reasons and became radicalised many years after arriving.
Far from being religious zealots, a large number of those involved in terrorism do not practise their faith regularly. Many lack religious literacy and could actually be regarded as religious novices. Very few have been brought up in strongly religious households, and there is a higher than average proportion of converts. Some are involved in drug-taking, drinking alcohol and visiting prostitutes. MI5 says there is evidence that a well-established religious identity actually protects against violent radicalisation.
The report also found that many of those involved had criminal backgrounds, and that the groups they involved themselves did not mind recruiting criminals:
"We have noticed that terrorist groups are remarkably tolerant of individuals with serious criminal histories. This is the case even when those individuals continue to be involved in very serious non-terrorist crimes, including drug-trafficking, assault and even rape".

If you have ever read any of the work of Scott Atran then this is definitely clear, and it's a good thing that the M15 and all are finally taking notice. He is a social anthropologist who has studied both terrorism and Islamism extensively and presented a number of lectures at the "Beyond Belief" conference criticizing the likes of Dawkins and Harris etc. regarding their claims that Islamic religiosity leads to terrorism.
I am not sure if any of his work is published online, but from what I have read of it previously, he has extensive data from his social sciences approach of studying thousands of Muslims in various countries to support his claims. It is well worth a look.
Ma`a al-salama