Both of these genres use scales unlike the well-tempered scale that art/classical/common-practice music of Western cultures uses. So I can see an amateur listener hearing those notes that sound *bent* or *out of tune* (according to what they were raised with) and thinking they must be from the same source. Even and Intro to Ethnomusicology class would dispel those notions. However - in fairness - unless you are talking about a truly isolated culture, people will hear things from others, and might choose to assimilate some of those elements in their own art, music, fashion, architecture, etc. we know for analysis that most indigenous cultures use scales that do NOT match the "factor of 12th root of 2" mathematics that generate the frquencies used in Western music. And most players will STILL bend the intonation very slightly, to enhance things like raising the 7th step before a resolution, etc. There are many. We also will alter pitch to match other instruments playing with us - any professional flutist who has sat next to a professional oboist or clarinettist in an orchestra, knows that you will listen carefully, and *tune thirds*, etc. - it is part of the art. NOTHING is cast in stone - except digital stuff.
On a recent trip, our cruise ship had Eastern European string players entertain. They played perfectly appropriate Haydn trios, etc. - and then - on the SAME violins, cellos, etc - played ethnic music, using the appropriate intonational inflection. People on the ship knew that we were professional classical musicians - so some (amateur guitarists, etc.) asked us WHY it sounded so different. And lately I have been routing the film "Blood Frets and Tears" - about rock-god guitarists. Film of them playing what most folks call shredding (to them, an insult . . .) on stage - and then, them playing flawless 4-part Bach fugues in tapping. Music is in the EAR - not in the instrument. You build an instrument to express what you want - or you change your playing to accommodate the vagaries of what you built. I have a TOP hand-made flute - and all of us who do, will tell you that it is far from perfect. NOTHING is perfect. that is what makes it human. To quibble over WHERE certain characteristics came from, is either a homework assignment from a middle-school teacher - or it is people with some kind of racist/ethnicist. agenda. Why a cutaway? Why a split E key? Why a Fast-system bassoon? Why steel strings, not gut? And how did GOOD BEER get to Mexico? (Polish and Czech farmers - ships found they could bring them in thru Galveston year-round, when NYC was iced up.) If you want NOTHING FROM ANYONE except those of your super pure-blood ancestors - well, good luck with that.