Here is my anecdotal story, my friends are both PHDs at Goethe University, the husband is German and a top research scientist, aggressive and obsessed in his work and field, his wife is Swiss, she now works in an important role in the Dean’s office, and tells me that she never wanted to be a PHD, she only wanted to raise a family and live a normal life.
BINGO!!! Mommy Tracking! In addition, women usually take more "secure," less dangerous jobs in general thus the lower pay. I love how all the feminazis leave this "inconvenient truth" out of their incessant "wage gap" studies.