The origins of flamenco are one of those hotly debated issues which I don't think anyone can really prove. They may have even been some cross- influence of flamenco back into Turkish and other Middle Eastern dances. None of this stuff is that clear-cut and proven. Antonio Gades did one hell of alot to turn this image around.
Legitimacy is another thing entirely.
This is, without a doubt, a legitimate art form. You want to know about Gypsies in the last 2-3 centuries in Europe, read Isabel Fonseca's Bury Me Standing . Saw a few other really good Zambra Moras during that time, too. Laurel teaches Russian Gypsy theater dance. You recently requested some info.