ethnoetiology

The story

1. Proto-Indo-European*swé
2. Proto-Indo-European*dʰeh₁-
3. Proto-Indo-European*swe-dʰh₁-
4. Proto-Hellenic*séswōtʰa
5. Ancient Greekἔθω (éthō)
6. Ancient Greekἔθνος (éthnos)
7. Englishethno-
8. Proto-Indo-European*h₂ey-
9. Ancient Greekαἰτῐ́ᾱ (aitĭ́ā)
10. Proto-Indo-European*leǵ-
11. Proto-Indo-European*lóǵos
12. Proto-Hellenic*lógos
13. Ancient Greekλόγος (lógos)
14. Ancient Greekαἰτῐολογῐ́ᾱ (aitĭologĭ́ā)
15. Latinaetiologia
16. Englishetiology
17. English todayethnoetiology

From ethno- + etiology.