You're all incorrect.

If you take a look at Googles Ngram Viewer it examines scanned texts and finds the earliest and most frequent, etc., occurrences of words.

"Genocide" first appears in 1808, but a minute fraction in publications. It picks up in ~1902, probably to do with the Armenian genocide. When you take out the smoothing (as I did in this link) it's easier to see the blips on the history of it. In 1940 the graph starts to rise and by 1971 it has really taken off.

I deleted a lot of nasty stuff here and in the coin toss threads. If Don and Steve don't stop the personal sniping I'll close both threads and people may find themselves in time out.