The children of criminals and dissidents are sent to institutions where they are trained to kill themselves in a public ceremony upon reaching a certain age.
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There's a subspecies of unintelligent, fast-growing humans used as farm animals and sometimes pets. They are all female, though, and must be fertilized by regular men. They also instinctively recognize and obey their close relatives. Now, a farmer hasn't been able to keep up with his growing livestock for a while, but his son finally became old enough to start pitching in. They hope genes from his beautiful mother will be expressed.
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Closed institutes for prisoners, orphans and/or various others are required to keep them contained, but apparently not alive. So they have unofficial procedures for killing them when they want to reduce the load, instill discipline, or even entertain the inmates or staff, but it's not considered executions.
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Clones are quickly grown and programmed and sent out into the world, but each batch has a recall date that they're not allowed to live past. So as that day approaches they allow themselves to be killed in various ways, some picked out as they go about their lives, some gathering for something more organized.