So they turn into suicide-bombers at the age of 20 or even sooner, mature at the same rate as humans and are preventively (and sometimes randomly) killed ... and that has been going on for ages.
I wonder how they haven't gone extinct yet. They would have to breed from the earliest possible moment just to maintain their population. Maybe they give birth in litters? Realistically the slums must be full of pregnant 12-19 year olds.