Somehow I find this article played a intellectual trick on people. The
biggest problem (and there are some others) is that the author assumes that all four person live to 100 years old. In actuality, none of them will. The probability of these four individuals of reaching 90% mortality rate is well documented in the insurance business and is likely to be much smaller than 100. When you average out the income with say 75 or 80, the differentials will be more significant.
There are also obvious socio-economical variables that the professor failed to mention.
Anyway, it's an interesting article, but I would take it with a grin of salt
.