Most of us can understand the reasons for youngest 20-somethings are living at home: they're still in school. But after 25, the starts to wane. So what's going on today?

You hear a lot of reasons: it's too expensive. No jobs. Too much college debt. All have a grain of truth to them. But the one we hear most often is that it's parents' fault. Parents today coddle their children to much. They hover and never cut the chord. They built up their too much. And on it goes.

It's certainly true that parents of this generation have invested heavily in their children. When I was a kid, my mother--bless her heart--told us to go out and play, and stay there. In February. In far northern Iowa. She bundled us up in cat-in-the hat stocking caps and shoved our feet into buckle-up boots that were impossible to get on over shoes (I was always of my BFF Lisa who sported the faux leather glory of a boot that didn't require shoes.) We scattered to our snow forts and toboggan hills and proceeded to ward off frost-bite and dodge rocks as we raced down Duncomb's Hill toward the frozen river below. Can you imagine?

Today kids would be organized in car pools for a scheduled run of the hill, and the hill itself would probably be leveled off, groomed of rocks, and redirected to a much less perilous landing. The toboggan run would probably be timed and there'd be ribbons involved.

The point is, , and families, have changed, for many reasons and to many effects. For one, families have grown smaller, meaning there is more time (and money) for each child. In contrast to the past, when families were large to ensure more workers on hand, children are now, as Norwegian scholar Ivar Frones says, rendered useless economically but priceless emotionally.

Families are also closer and less divided by generation gaps today. According to the National Opinion Research Center, youth today are more likely to find agreement with their parents than their counterparts in the 1970s and 1980s. The closing of gaps is often strongest for the most volatile topics, including abortion, roles, , and civil liberties. Indeed, several of the young adults we interviewed for "Not Quite Adults" spoke of their relationship with parents as a work in progress, and they were discovering a growing appreciation for their parents. We also constantly heard, "my mom is my best friend." And as parents, we're still feeling the reverberations of the 1980s child-snatching/child danger scare, which indirectly led to the rise in scheduled and parent-policed child play.

While I was researching "Not Quite Adults," I went back through a bunch of parenting advice books over the years. Talk about fascinating. It was also like watching a tennis match. Back and forth the advice changed with each new guidebook and each new generation of mothers. Coddle your children. Don't coddle your children. Regimes and schedules are critical. Let children explore on their own. Follow science. Follow your gut. And on and on. But one thing remained constant. Motherhood was a vocation, and mom was in the hot seat for the care and development of the next generation.

The only reprieve mom got was a brief one in the early 1990s. Amid growing research on the importance of the first three years of life to brain development, activists began to argue that families needed more outside support to help them during these critical years. The country needed better child care, better health services, communities should be mobilized and government and business should develop more family-friendly policies. It was the first time that the spotlight was turned outward, away from the inner family, placing shared responsibility on raising the next generation with society and not just the family. It almost goes without saying that that burst of magnamity was short-lived. Mom and dad were soon back in the hotseat all by themselves.

If it was clear that the family was responsible for the success of future generations, it was also clear that a century of science had produced little hard evidence that the myriad "methods" of childrearing had much effect one way or another. Although science certainly made enormous leaps over the century in understanding , it also found itself, by the turn of the twenty-first century, with no clear-cut grasp on what type of parenting worked best.

Barring the most egregious home conditions, studies in in fact were beginning to cast doubt on the centrality of the home environment on children. A study of identical adopted by different parents showed that they were uncannily similar in their behaviors and outlooks, even though they were reared by different parents in different homes. As a scientist told Ann Hulbert in "Raising America," "the implications are that parental behaviors have no effect, or the effects must vary greatly from one child to another in the same family."

All this is a backdrop to where we stand today. Parents are once again in the spotlight, being blamed for coddling their adult children, not the cord, not "letting go." They are also beginning to be bombarded with advice and opinions about what to do if they find themselves in this embarrassing state of supporting a twenty-something child. Kick them out, the school of hard knocks is best. Don't coddle young adults.

But just remember this: the worry that parents are raising a generation of dependent children has a long and storied history. With a note of disgust, the Surgeon General in World War II declared three million World War II recruits unfit for duty because they could not stand on their own two feet and face life. During the next war, Harry Truman worried about coddled soldiers in Korea. The parents of the ‘60s flower-power and anti-war protesters had been too permissive, raising a generation that didn't respect authority. Too much Spock, not enough .

In all the rhetoric, one message rang out: parents had somehow failed. Similar suspicions linger today: have we raised a generation too willing to coast along on mom and dad's support? Have we spent too much time raising their self-esteem and not enough time making them face the music? Have we erred on the side of overscheduling them to the point that they are lost and aimless without an adult and a schedule? Have we given them everything but made them lazy?

I seriously doubt it. Sure there's always exceptions and some parents are way too involved in their young adult's life. But for the most part, we're muddling through-- in a different climate, during a different era, and with a different set of guidebooks. My coauthor Rick tells the story of worrying aloud to his pediatrician about the lack of progress in potty training for one of his kids. "I wouldn't worry," the doctor counseled, "I've never yet seen a bride walking down the aisle in diapers." The same can be applied to young adults. They're not going to remain in a state of limbo forever.

What I do sometimes wonder, though, is whether all this parenting blame is a red herring, shining the spotlight away from some larger problems in society that are making this path to adulthood a longer and more winding one. It's certainly easier to blame mom and dad than it is to think about reordering some of our institutions to provide supports to young adults, or to do the heavy lifting of fixing our educational system, or all those other complicated and seemingly impervious "systems" that guide and shape our lives and our fortunes.