>>83
Biologically, it can easily be shown that females aren't ready to reproduce before the age of 12-14 years old, when their periods begin. The situation can be inferred to be similar for males.
Mentally, (save a few mathematical geniuses) they're not logical enough to fully asses the medical and social issues of sexuality, nor do they have the information required (or the capacity to comprehend it) to take such a decision.