That is a MAJOT probel here in leftist New England. Many of the 'adults' are chronologically thirty years old, but are roughly five or six mentally. It is an amazing cultural phenomenon...undisciplined brats growing into undisciplined adults. Frightening.
Related book title are interesting:
An Adult Child's Guide to What's "Normal"
Perfect Daughters
Codependence: The Dance of Wounded Souls
Healing the Adult Child’s Grieving Heart
Getting Along (Almost) With Your Adult Kids: A Decade-by-Decade Guide
Ready or Not, Why Treating Children as Small Adults Endangers Their Future and Ours
Geez...'MAJOT probel' = 'major problem'. More coffee, please.