But yeah, that's what I was basing my argument about it not really being sexism when it comes to employee evaluation; just some biology and stuff.
Well, I'll just leave you with this little excerpt from the study which addresses exactly that:
"For example, Budig and England (2001) examine differences in work
patterns between mothers and nonmothers and find that interruptions
from work, working part-time, and decreased seniority/experience collec-
tively explain no more than about one-third of the motherhood penalty.
They also show that “mother-friendly” job characteristics (i.e., differences
in the type of jobs mothers and nonmothers choose) explain very little of
the penalty. Similarly, Anderson et al. (2003) find that human capital,
occupational, and household resource variables (e.g., number of adults in
the household) collectively account for 24% of the total wage penalty for
one child and 44% for women with two or more children. Likewise,
Waldfogel and Meyer (2000) find that occupational controls do not elim-
inate the penalty. As Budig and England (2001) conclude, the remaining
wage gap likely arises either because employed mothers are somehow less
productive at work than nonmothers or because employers discriminate
against mothers (or some combination of the two processes)."