Actually what you speak of has very little to do with "being an adult" and almost everything to do with western cultural values towards family. It's well known in western society, primarily upon caucasian individuals that they value independence and being on their own. But in other cultures, such as latin and asian based cultures. family is a much more important aspect, with traits that you criticize are consider normal. For example, I'm not certain this is true or not, but I was told that supposedly in mongolian culture, people are allowed to get breast milk from their mother indefinitely. There isn't a certain amount of time like say 3 or 4 years old and than you stop. So supposedly it's normal for a 50 year old to drink the breast milk of their mom. That's their culture. And has nothing to do with being an adult or not.
Now of course that's an extreme example but I can perhaps provide one that's not so extreme that may provide a better example, a personal situation per say that I haven't told that many people about. I have two older sisters who I'm extremely close to, but they live in different areas. Now I'm adopted and my sisters are caucasian, but very often we are compared to a latin family for how close we are. An example of this is not long ago, my oldest sister whose currently married was very concern over my well being and wanted me to move in with her and her husband so they can look out for me. Yet she made this decision without her husbands "consent." My brother in law doesn't really like me but that's a different story. In the end, my brother in law did not want me coming but my sister did. And now ultimately they are separating. My brother in law, by the way, is caucasian.
Now for the few that I have talked to who are hispanic ( I live in san diego no more than 10 minutes away from the border, so the majority of my friends are mexican.) they all uniformly believed that the brother in law was wrong. Not a single one sided with him, saying how dare he try to come between my sister and I and etc etc. However, for the few close caucasian friends I have, the majority (not all) sided with the husband. Saying that with them being married, the husband is the most important aspect and what he said should've gone.
It provided a very interesting cultural boundary that I found between different ethnicities, even though my family is caucasian lol. I can provide many other examples, such as my long trip in Japan, they also had a very close bond on family. For example, in Japan, it's very normal for a married couple to stay within their parents house and the parents and married couple combine will help save money to buy the married couple a house.
In the end, the reason why I'm telling you this is to not change your mind regarding your views on if you like this sort of behavior or not, but to show you that it has nothing to do with "being an adult." Essentially, there are just people who are closer towards their family than others. (well technically the majority of the world seeing as it appears that primarily caucasian culture appears to have this huge pride on independence and distance from their family. As Asian, Latin, and African cultures seem to place supposedly a greater value on family.)
I have a decidedly different take on this issue. During the time when the U.S. was primarily an agrarian society, family was more valued, among all races, as everyone was needed to pitch in take care of the family farm. With the onset of the industrial revolution, families started to separate and become more independent because they needed to make a living to support themselves and their future families.
I recognize the values of self-reliance and independence as American traits, not restricted to any one race. But, I'd further argue that historically African Americans were forced to be independent and grow up quickly because families didn't have the means to support the family. So, it was necessary for everyone to work, as soon as they could. Children often didn't finish even grade school because they had to go out and seek jobs, any jobs, to earn a bit of money that was pooled together for the family. Families stayed together because they had no other choice, based purely on economic reasons. So, you often had multiple generations living together, the grandparents, parents and children.
As the economic fortunes increased for everyone of every race, families became significantly more fragmented. Children graduated from High School and those who could attend college did, often in different cities. Children who elected not to continue their education looked toward factory employment as the jobs of choice. The big boom in the Automotive and Steel industries resulted in a great migration of people to the Midwest to take advantage of the higher paying factory jobs in those industries and more young people left home seeing this as the opportunity for them to have a a bit of financial freedom.
Throughout the years, up until the 90's, this trend continued and young people of all races, left the nest upon graduation. During this time, though the economy improved, African Americans always lagged in employment and economic advancement. The one message that was ALWAYS clear in the Black home was that you needed to be self-reliant, independent and educated. You were NEVER coddled because your parents understood that you'd enter a world of prejudice that wasn't able to coddle you, and so you were taught to be resilient and tough against the realities of the problems you'd face. If you left home, you left, period, you were on your own. Your parents didn't have the finances to support two households, theirs and yours. You bought your own food, always, you paid your bills and washed your own clothes. You were taught to stand on your own two feet. It didn't mean that if you stumped your toe, they wouldn't help you, if they could, but you were expected to get back up and make it in the world as a man, period. So, yes, in was very much about growing up.
For the first time in American history, parents have been fortunate enough to have sufficient resources to "help" their children. I think, partly, because of the difficult times that they faced, parents have been less insistent on forcing children to grow up and assume responsibility at the same age when they themselves were out working, creating families and forging their way in the world. It's unfortunate, in my opinion, because I see a group of young people, dependent on their parents and filled with expectencies. It's epidemic within all communities, White and Black and all other ethnicities. Children think that their parents have a duty to help them, buy them cars, trucks, gaming equipment, while the children wile away their time with the luxury of "trying to decide" what they want to be when they grow up. As a result, there's much less respect for the value of things and people. If you never have to work for something, you certainly don't respect it as much. If you don't get what you want, what the heck, just take it from someone less fortunate.
The media doesn't help with marketing that tells young people that they should have the best, the nicest cars, the most beautiful women or handsome men, and it should be theirs now. This is far different than the message that their parents and grandparents received, that you had to wait, wait for what you wanted until you could afford it, until you worked for it, until you completed your education, on and on..
Ultimately, self-reliance and independence as more important than they ever were in this country. There're many more people competing for fewer resources and without those traits, people will get lost in the mix. But, what I see is far fewer younger people actually growing up, or being made to grow up, and forced to taste reality for what it is.
Does it mean that EVERY young person is lazy and unwilling to step up to the challenge, no. Does it mean that families haven't fractured creating single mother households where children have become uncomfortably close to mothers, no. Is it wrong that these situations occur? I guess that depends on how it affects the dynamics of the relationships that those young people enter in life. If it paralyzes them, disallows them from developing normal connections to families that they create, then I'd say, IMO, yes. Otherwise, they must deal with the issues in their lives and find a way toward healthy relationships. For some it'll happen sooner, and for others it may be a life long search.
That's my two cents, not fatherly advice, not pontification, but an understanding of history in this country, discussions with parents, friends and my own observations. If the shoe doesn't fit, so be it....