"Electro: Where is it from? What are its subgenres?"
Were the Euros its Godfathers (Kraftwerk etc.) as is often claimed? Or was it Yellow Magic Orchestra? (after all where you think them drum machines came from lol)
Is it the logical stepchild of 80's funk that was already heavy on synthesizer and electronic drums?
Did the east co-opt it first with Planet Rock? Did this original spark later give away to groups like Mantronix, Newcleus, the Aleems, Captain Rock etc.?
There are several Detroit entries in the electro annals, Cybotron was probably the earliest, and I always liked Drexciya cause of the conceptual premise of their music (their music was created by slaves who fell / escaped from ships during the middle passage and fell to the depths of the sea, eventually growing lungs and becoming inhabitants of the deep) though they were much later. Detroit and for lack of better words 'urban' electronic music to me always seemed to go hand in hand.
But when electro settled in the West Coast, Cali seemed the most at home with it. Whole styles of dance were based off electro. LA was late to breaking and graffiti so the same way New York will always have sentimental attachment to 'the breaks', maybe LA will always have similar attachments to 80's funk and electro?
The wiki entry for electro gives these groups
Afrika Bambaataa Aux 88 Anthony Rother Arabian Prince Arthur Baker Cybotron Cylob Davy DMX DMX Krew Dopplereffekt Drexciya Dynamix II Egyptian Lover Freeez Hashim Imatran Voima I-F Jackal & Hyde Jonzun Crew Kraftwerk LA Dream Team Maggotron Man Parrish Mantronix Michael Jonzun Midnight Star Model 500 Mr Velcro Fastener Music Instructor Newcleus Warp 9 Planet Patrol Ryuichi Sakamoto Scape One Tyrone Brunson Volsoc World Class Wreckin' Cru Yellow Magic Orchestra