NONE of those things you have typed make it impossible for that teenage girl to become a good parent.
I WAS that teenage girl. In all but one way. (I was never beaten up by a parent's ^dealers, just by my mother and stepdad...).
I absolutely DETEST the inference by SW's that if you have been abused or seriously neglected yourself, that you will abuse or seriously neglect your OWN children. You may not have had a good model of how a childhood should be, but more often than not, WITH the right support and teaching you CAN become a good parent.
It may mean paying out for residential care for the mother and child/ren, which I know costs more money (that's the reson SS wanted ME to stay in an unsupported bedsit rather than the M&B unit - because it would have to be paid for from the 'leaving care funds' and it was twice as expensive), but gives the right teaching and support.
With that help, I learnt what it takes to run a house, cook nutritious meals from scratch, got a qualification in first aid, went to college and then on to a degree course, what a child's development milestones are, how to access NHS support for special needs children, how to do laundry, they taught me how to PLAY with children of different ages (not something I had ANY idea how to do before that), and many many more things.
Now, 13 years later, I am a Lone Parent to 4 dc, 2 of whom have SN, my 13yo DD is just about to choose her options, I have a 9yo who is preparing to take his 11+, an 8yo, who despite being ready to go to an SN school at 4yo, is now working at the average level for his age group in mainstream school, a 1yo baby who is meeting all his milestones. I help out with reading at the older DS's primary school once a fortnight when DS3 is with his dad (i.e. I pass a CRB check), I have a tidy house, I make and decorate cakes from scratch for my friend's dc's birthdays, I love playing board games with my dc even if DS1 does always thrash me at monopoly. People are happy for me to look after their dc. I volunteer at a support group for dc with special needs. I make sure my dc are clean, well fed, get to school every day, homework done, I make sure that my dc get enough exercise and are a healthy weight.
NOW, I doubt SW's would look twice at my dc. So I get really rather agitated when I hear people say that someone who has been abused or neglected is going to do the same to their own dc like it is inevitable. IT ISN'T.