[dredmorbius]

I'm not an area expert, and of course don't know what you were taught, or even what general pedagogy over recent decades has been.

I suspect that strong confirmatory evidence came through awareness and analysis of mitochondrial DNA, a term which begins apppearing in Google Ngrams as of the 1960s. Full DNA analysis likely wouldn't have occurred until the 1990s or early aughts, when full genome sequencing became available, so the point might have been argued until then. It strikes me as a rather rear-guard objection at that point however.

(I'd tried a few times to make a clearer assessment of when the view became mainstream, with inconclusive results, though "proposed in the early 20th century, largely substantiated in the 1960s, and all but sealed by 2000" seems a fair statement.)