because a child live whole day with mother not with father
But this is the opening statement of the article:
In families with two working parents
Without reading the rest of the article, the title makes sense because we know that the male tends to use more sophisticated vocabulary (yes I realize this is a generalization)... but learned this from that BBC video on youtube about fatherhood. The link was posted on BK some time ago:
http://www.youtube.com/v/KtG7kYf4x8M&rel=1