i see this all the time, people will adopt a fully grown man, like 20 years old, as if they're adopting a kid
that's the age where you're no longer in need of care, you are able to live on your own, are allowed to work and have all the rights and expectations of an adult, but they adopt them the same way they would adopt a little child
sure some of these people have been orphans since a young age, but it seems odd that they'd stay in that system past the age where they're reliant on adults
the thing is, these are pretty much always criminals or 'troubled youths', you hardly see decent kids who got a bad share in life and end up orphaned get adopted into a family long after they've grown up into adults, they just carry on in life as adults
it's nearly always delinquents
which leads me to believe this is less "adoption" and more of a system of throwing problem people onto families to make them their issue, cause suddenly if the dude you adopted is going around causing problems, it can be reframed as "child of [family] commits a crime" which puts the responsibility on the family despite not having raised him, as opposed to "orphan raised in the care system commits a crime after leaving it" which puts the responsibility on the system