The authors interviewed 25,000 men and women who graduated from Harvard Business School over the past several decades and found that the "opt-out" explanation is a myth because women are allowing their partners' careers to take precedence over their own, News.com.au reported.
Among Gen X and baby boomers they surveyed, only 11 per cent of women stopped working to be full-time mums, while 74 per cent of them, who are currently 32-48 and in the prime of their child-rearing years, work full time, an average of 52 hours a week.
When they graduated, more than half of male HBS grads said they expected their careers would take precedence over their partners', but only 7 per cent of Gen X women and 3 per cent of baby boomer women said they expected their careers to take precedence.
The study also found that the majority of women said they assumed they would have egalitarian marriages in which both spouses' careers were taken equally seriously.
About 40 per cent of Gen X and boomer women said their spouses' careers took priority over theirs, while only about 20 per cent of them had planned on their careers taking a back seat.
However, more than 70 per cent of Gen X and boomer men say their careers are more important than their wives' and a full 86 per cent of Gen X and boomer men said their wives take primary responsibility for child care.