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| Hermaphroditus, wall painting from Herculaneum |
In the previous post I mentioned that in biological
chimeras (individuals formed by the fusion of two independent fertilized eggs)
it may happen that most of the body belongs to one sex, but the genital organs
belong to the other. This phenomenon is called pseudohermaphroditism.
It can also be the case (although it is rarer) that the same individual has the
two genital organs, complete or incomplete. This phenomenon was formerly called
hermaphroditism, name of a son of Hermes
and Aphrodite in Greek mythology, but these cases have recently been included in the concept of intersex, a more general term that covers all cases that do not fit the usual definition of male or female bodies, reserving the word
hermaphroditism for animals or plants where that condition is normal.
To clarify things, normal
members of the human species have 46 chromosomes (23 pairs), with
pair 23 formed by the two sex chromosomes, which are responsible for the
differences between the sexes. They can be either two X chromosomes (one inherited
from the mother, the other from the father); this genetic endowment is called
XX and the individual is female. Or they can be an X chromosome (inherited from
the mother) and a Y chromosome (inherited from the father); this genetic
endowment is called XY and the individual is male. But in addition to these two
cases there are others, much less frequent. Let us quote a few (frequency figures are taken from Wikipedia):
