As best as I can tell from a cursory look it originates from this research originally published in 2012: https://www.microsoft.com/en-us/research/wp-content/upl

As best as I can tell from a cursory look it originates from this research originally published in 2012: https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/WhyFromNigeria.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/... Via the book Think Like A Freak which I’d guess extrapolates from it. But it seems like one of those ideas that has gone from plausible explanation to fact in popular imagination.