No-one connected to the attacks has yet turned out to be from Syria - they were almost all (around 12 so far) EU citizens from France and/or Belgium. There appears to have been at least one Algerian and possibly one or more Moroccans involved indirectly, but no evidence of any Syrians. Many of them grew up in urban Brussels. Many had travelled to Syria for training/recruitment (not agriculture). They were largely aged late 20s to early 30s. Young adults would fit better than "youths", only one (aged 20) could really be called a "youth".
Likewise, everyone named so far in connection with the 22nd March 2016 Brussels attacks, believed to be linked to the Paris attacks, has been a Belgian national.
There are, however,
four three (as of 9th Dec 2015) whose identities and background are not yet confirmed.
Many news outlets list their known biographical details, e.g. BBC, which is the source for most of the below. There are also lists and details on Wikipedia, and NY Times:
Directly involved in the initial Paris attacks
- Abdelhamid Abaaoud, 28, suspected ringleader, Belgian national, grew up in Brussels
- Salah Abdeslam, 26, escapee arrested March 2016, French national born in Brussels
- Brahim Abdeslam, 31, suicide bomber, Salah's brother, as above
- Unknown third man believed to have been with the two brothers
- Omar Ismail Mostefai, 29, French national, born in Paris, Algerian ancestry. Suicide bomber in the Bataclan.
- Samy Amimour, 28, French, Paris resident, another Bataclan suicide bomber
- Foued Mohamed Aggad, identified on 9th Dec 2015, 23, French, from Strasbourg, travelled to Syria in 2013
- Bilal Hadfi, 20, French national living in Belgium, stadium suicide bomber
- Unknown stadium suicide bomber carrying a Syrian passport believed to be fake, possibly copied or stolen from a dead Syrian soldier under the name "Ahmad al-Mohammad". Matched fingerprints of a migrant registered in Greece, otherwise, identity unknown.
- 'M al-Mahmod', unknown origin, possibly fake name, traveled with the above. A picture released by the French authorities shows him looking to be aged late twenties to early or mid 30s.
Police raid in Paris shortly after the attacks
- Hasna Aitboulahcen, 26, French daughter of Moroccan immigrants who died during police raid. Level of involvement in the attacks and circumstances of death currently unknown.
- Jawad Bendaoud, 29, arrested during raids, rented the flat used by the attackers. He's described as a "Frenchman" and a long term St Denis resident.
- Chakib Akrouh, 25, a Belgian-Moroccan citizen, who blew himself up during this raid
Accomplices of Salah Abdeslam
- Mohamed Abrini, 30, Belgian, from the same area of Brussels where Salah Abdeslam grew up; a wanted suspect seen with Salah Abdeslam before the attacks
- (update March 2016) Possibly the first non-European involved (indirectly?) in the Paris attacks: Algerian national Mohamed Belkaïd, killed during a gunfight with police and suspected ("more than likely") of helping with the logistics for the attacks. He travelled to Syria to join ISIS in 2014 but, like the others, travelled from Europe, via Turkey.
- (update March 2016) Najim Laachraoui, 24, born in Morocco and raised in Brussels, and travelled from Europe to Syria in 2013. Was a wanted suspect believed to be an accomplice of Salah Abdeslam who helped him escape, and his DNA was found on explosives used in the Paris attacks and in two properties raided in connection with them. He is also believed to be a bomb-maker involved in the 22nd March 2016 attacks in Brussels (see below).
Other / unknown / uncertain role
- (January 2016) Zakaria J, Belgian, 30, arrested on suspicion of involvement, role unknown
- Ahmed Dahmani, 26, Belgian (of Moroccan origin), arrested on arrival in Turkey the day after the attacks
- (January 2016) Gelel Attar, unknown age, Belgian (of Moroccan origin), arrested in Morocco, role unknown
- (Feb 2016) Zouhir Mehdaoui, 29, Algerian former resident in Belgium, arrested in Algeria, role unknown
- Hamza Attouh, 21, Belgian (arrested for helping Salah Abdeslam to escape).
There's a list of such people on the Strait Times, here. I've omitted several who were arrested and since released (inlcuding "Ayoub B" mentioned in an earlier version of this post).
Brussels attacks 22nd March 2016
While not officially confirmed, it's believed that these attacks were linked to the Paris attack, believed to have been planned and committed by people involved in the Paris attack. It's suspected that it might have been originally planned for later in the year, then bought forward and rushed as members of this group were arrested or named as suspects based on the Paris attacks investigations.
- Najim Laachraoui. See above, under "Accomplices of Salah Abdeslam" - he was initially believed to be as) a third man who transported explosives with two suicide bombers, but is now believed to have been one of the two suicide bombers. Le Monde claim this is confirmed with DNA evidence
- Khalid El Bakraoui, 27, and Brahim El Bakraoui, 30, brothers, believed to have been suicide bombers in Brussels airport (Brahim) and metro (Khalid). Khalid is believed to have rented an apartment raided in connection with the Paris attacks, used by Salah Abdeslam before his arrest. They are described as Belgian nationals and had criminal records in Belgium dating back to 2010 (Brahim) and 2011 (Khalid). Interpol confirm that Khalid was born in Brussels.
- An accomplice of the two suicide bombers in Brussels airport, not yet identified
- Possibly, a second (failed?) Metro bomber, according to CCTV footage, not yet confirmed or identified
BBC graphic to help clarify the links:
Police raids following Brussels attacks