Too long and incoherent to be on the comment page...

Article or no article, people lived at home longer before, end of story. For the most part, Abs, you're right, as soon as you got married you left the house (if you were a woman) but in most cases even then, people did not get married until they were in their late twenties or sometimes later for males. Now Europe has a different story than America does as far as this goes, but for the most part they are kind of similar. And it only applies to the top ten percent of the population, the wealthy sons. Only the sons of the wealthy were able to leave the house for such things as travel and to attend differing universities all over Europe, often the further away from home and their father (damn that teenage rebelliousness). The whole time they are gone, much like what occurs later in life (they get an allowance) they are dependent upon their family estate and parents to keep sending money (sound familiar). When the money either dries up, they no longer have any travel/learning left in them, or perhaps they get into trouble, they come back home. Until they are married, they come and go from the family estate, always dependent upon it. So even when they move away, they always depend on that. But again this is only the wealthy portion of the population and thus a very very small percentage. The rest of the people, especially in a time that is pre middle class, and pre industrial revolution, the poorer populations tended to have many generations living under the same roof. As it is in some cases today, even middle class families throughout Europe tend to have multi-generational living (like in Spain for instance). the nuclear family structure is different.
In America, the nuclear family has been somewhat been altered in the past fifty to eighty years or so and going through a flux of change as it has been throughout the world (the world living in a post post industrial age) and most of the studies for your article have probably looked at life in this duration of time, but seeing as this is such a short span of time, perhaps it is best not to look at trends still in flux. Perhaps another hundred or so years when historians and anthropologist look back and study this age, they will think quite differently on the subject as fifty or so years is only a hiccup in the span of things. For the most part, like Europe, only the wealthy moved away from the house at an early age. Pre-industrial revolution, when America was still a farming economy (such as at the time of Thomas Jefferson), things were much the same as they were in Europe (as America was still so very novel and most families were even first generation families from parts of Western Europe). Even when children moved out, when they were married and not before (males and females), they only moved out of the house. Usually their house would either be located within the family land, or right next to the family land within the same small stretch of land. This is due to many things, but most of all, it probably was due to inheritance laws and rituals. The inheritance laws and rituals remained somewhat the same as their ties with English law, but after a time, things became more democratic and not only one child would receive the bulk, but as time went on it was eventually split more fairly (though woman still wouldn't have a right to the land, except in dowry for a long time yet). In Europe and England in particular, the eldest male child would be set to take the bulk of it and then have to take care of his younger siblings (including his sisters, by providing a dowry), this also kept the younger children at home (at least on and off again when they ran out of allowance), and especially the women. But even after marriage, often the younger siblings would still remain at the patrimonial house. In most cases, the younger siblings, unless they were involved with a huge estate (and therefore a huge allowance) wouldn't be able to marry, as they were not nearly attractive enough (financially) and they were sent off to the seminary and joined the Cloth. This practice had been in place since the middle ages. This again is mostly dealing with the wealthier populations at the time, which made up a bigger percentage than at Europe at the time, because there were more people who owned land at the time as compared to with Europe.
The poorer populations in America were the populations most likely to move further away from the house pre or post marriage. This also reflects the fact that most settlers to America's shores were single men trying to gain their fortune with the hopes of returning home and settling down there. Obviously, it did not work out so well and a good thing too. But this did not mean that these men were any younger than an age we deem today as appropriate for moving out on our own. In most cases it was probably older still. These men who immigrated here, the early ones, were most likely to be the younger sons of aristocrats back home, who had no inheritance (meaning land) to settle on and therefore chose a place that could possibly make them money (of course so they could eventually return and buy their own land...). But as time wore on, the spirit of enterprise remained steady in the American Frontier. Those who kept pushing the boundaries, were of course those who did not have land. But in many cases, it was still herds of families pushing the boundaries together, as soon as they found a place in the wilderness, the families would once again congregate in that same area, calling (not literally but through letters duh) for friends and family to come join them in the surrounding land.
I am tired of talking about this for now, there is too much information in this simple little statement that a historian could write an entire book out of it. And at three in the morning, I just have no patience to sort out my jumbled mind and write a proper essay that is as much coherent as it is convincing. It is much easier to just say that you are wrong I am right, stick out my tongue and wave my bum in your general directions. If you guys want to still disagree just for the sake of disagreement, then you can just go swivel or however you say it...
peace out peoples,
-sib-