Thus it seems that scholarly culture, and the taste for books that it brings, flows from generation to generation largely of its own accord, little affected by education, occupational status, or other aspects of class

I wonder what e-book readers like the Kindle will mean to these statistics. On the plus side, a lot of e-books are free and those that aren't are often discounted, so a family with a Kindle might be able to afford more books (assuming they can pony up for the device). But the books aren't as easy to share and you probably don't want your 5-year-old dribbling juice onto your fancy expensive gadget.

Want Smart Kids? Here's What to Do Buy a lot of books.

The same cannot be said of the fieldworkers, most of them childless graduate students seeing combat for the first time. “The very purest form of birth control ever devised. Ever,” said one, Anthony P. Graesch, a postdoctoral fellow, about the experience. (Dr. Graesch and his wife have just had their second child.)

The couples who reported the least stress tended to have rigid divisions of labor, whether equal or not. “She does the inside work, and I do all the outside, and we don’t interfere” with each other, said one husband.

In addition to housework, mothers spent 19 percent of their time talking with family members or on the phone, and 11 percent taking occasional breathers that the study classified as “leisure.” The rates for fathers were 20 percent chatting, and 23 percent leisure — again, taken in fragments.

Mothers still do most of the housework, spending 27 percent of their time on it, on average, compared with 18 percent for fathers and 3 percent for children (giving an allowance made no difference).

the U.C.L.A. project was an effort to capture a relatively new sociological species: the dual-earner, multiple-child, middle-class American household. The investigators have just finished working through the 1,540 hours of videotape, coding and categorizing every hug, every tantrum, every soul-draining search for a missing soccer cleat.

One researcher roamed the house with a handheld computer, noting each family member’s location and activities at 10-minute intervals.