I think it is natural for mothers to want to spend more time with their children than fathers, and a Pew study
http://pewresearch.org/databank/dailynumber/?NumberID=869 confirms this:
"Fully two-thirds of women with children ages 17 or younger work either full time or part time. Most have full-time jobs outside of the home (74%), but just 37% of working mothers prefer this role. A strong majority of working moms (62%) would rather work part time; a job situation enjoyed by just 26% of working mothers. Over a decade ago, just 48% of working mothers said a part-time job would be ideal. Today's working mothers look little like their male counterparts. Fully 79% of working fathers prefer to work full time, while just 21% say part-time employment would be ideal."
Now to the second assertion on sex discrimination. Studies find that all or nearly all of the income disparity between men and women is not due to discrimination but their choices of careers and how much they work. Christina Hoff Sommers debunked the 77-cent myth in
http://www.nytimes.com/2010/09/22/opinion/22Sommers.htmlFair Pay Isn�t Always Equal Pay
New York Times
September 21, 2010
...
But the bill isn�t as commonsensical as it might seem. It overlooks mountains of research showing that discrimination plays little role in pay disparities between men and women, and it threatens to impose onerous requirements on employers to correct gaps over which they have little control.
The bill is based on the premise that the 1963 Equal Pay Act, which bans sex discrimination in the workplace, has failed; for proof, proponents point out that for every dollar men earn, women earn just 77 cents.
But that wage gap isn�t necessarily the result of discrimination. On the contrary, there are lots of other reasons men might earn more than women, including differences in education, experience and job tenure.
When these factors are taken into account the gap narrows considerably � in some studies, to the point of vanishing. A recent survey found that young, childless, single urban women earn 8 percent more than their male counterparts, mostly because more of them earn college degrees.
Moreover, a 2009 analysis of wage-gap studies commissioned by the Labor Department evaluated more than 50 peer-reviewed papers and concluded that the aggregate wage gap �may be almost entirely the result of the individual choices being made by both male and female workers.�
In addition to differences in education and training, the review found that women are more likely than men to leave the workforce to take care of children or older parents. They also tend to value family-friendly workplace policies more than men, and will often accept lower salaries in exchange for more benefits. In fact, there were so many differences in pay-related choices that the researchers were unable to specify a residual effect due to discrimination.
<end of excerpt>
A good book on the subject is "Why Men Earn More" by Warren Farrell . It is summarized at
http://www.warrenfarrell.net/Summary/index.html .
Apart from empirical studies, Economics 101 says that in a free market, if some firms pay men substantially more than women for the same work, they will be outcompeted by firms that firms that do not discriminate.
