My nephew is an immature man-child - he's made his mother's life a misery, and he's in his early 30's now!
A string of written off cars, motoring offences with short periods of being banned, a string of broken relationships, a few children he's left behind to be looked after by their mothers, convictions for low level crime, a string of jobs where he's been sacked and a wrecked credit rating, not to mention unable to rent a home in his own name because he can't get a "good" reference from any of his past landlords (due to unpaid rent, damage and being evicted legally a few times).
His latest wheeze is to change his name to his mother's maiden name and "steal" his dead grand-father's identity by taking out loans, credit cards and car insurance using his grandmother's address (who is in her 80s with dementia). His initials are the same as his grandfathers, so it's been very upsetting for the grandmother to start getting letters, default notices, etc in her dead husband's name! He never even goes near their house to pick up "his" mail, so clearly has no intention of paying his debts!
Between living with numerous girlfriends (he has to move in with them as he can't get a home of his own so only "targets" women with their own home, either rented or bought), he comes back to his mother, tail between his legs, promising to change his ways, etc., just to get a roof over his head, and then a few weeks later, he's found a new "victim" to move in with and the cycle repeats itself until new girlfriend gets fed up of his freeloading, abuse, etc - if she's lucky, she won't have got pregnant by him, but he has 4 kids and counting, none of whom he sees nor pays maintenance for.
As for jobs, it's just a succession of dead end jobs, usually "off the books", as he can't show references as he always gets sacked, but it's never his fault!!
OP needs to be very careful. My sister started down that road of being used and abused by the "he's only 21" type of thinking and all it's done is facilitate his reckless and selfish lifestyle.