  Despite increasing representation in graduate training programs, a
disproportionate number of women leave academic research before obtaining an
independent position. To understand factors underlying this trend, we analyzed
a multidisciplinary database of Ph.D. and postdoctoral mentoring relationships
covering the years 2000-2020, focusing on data from the life sciences. Student
and mentor gender are both associated with differences in rates of student's
continuation to independent mentor positions of their own. Although trainees of
women mentors are less likely to take on independent positions than trainees of
men mentors, this effect is reduced substantially after controlling for several
measurements of mentor status. Thus the effect of mentor gender can be
explained at least partially by gender disparities in social and financial
resources available to mentors. Because trainees and mentors tend to be of the
same gender, this association between mentor gender and academic continuation
disproportionately impacts women trainees. On average, gender homophily in
graduate training is unrelated to mentor status. A notable exception to this
trend is the special case of scientists having been granted an outstanding
distinction, evidenced by membership in the National Academy of Sciences, being
a grantee of the Howard Hughes Medical Institute, or having been awarded the
Nobel Prize. This group of mentors trains men graduate students at higher rates
than their most successful colleagues. These results suggest that, in addition
to other factors that limit career choices for women trainees, gender
inequities in mentors' access to resources and prestige contribute to women's
attrition from independent research positions.
