"I think the OP's sister has taken a really unusual route." Maybe that's true, but for positions like the one she's in, the educational background tends toward

"I think the OP's sister has taken a really unusual route." Maybe that's true, but for positions like the one she's in, the educational background tends towards the humanities, not towards STEM degrees. Also, I always assumed that English PhDs take forever because people do it part-time, which is usually not an option with STEM degrees (although is often an option in CS).