Part mortal, part something else, the planetouched are loners and
individuals. The origins of the various kinds of planetouched are as
different as the forms of the planetouched themselves. In Calimshan, Efreets
and Djinn mated with their human slaves, and thus Air and Fire Genasi were
born. In Mulhorand and Unther, incarnations of deities mated with favorite
humans to produce Aasimar and Tieflings. In the High Forest, Sun elves bred
with Succubi to produce the Fey'ri, while orc shamans called demons to breed
the Tanarukk.
The child of an outsider, and another creature is a half-fiend, It is the
children of these creatures' children that are usually planetouched. The
offspring of two planetouched is always a planetouched which takes after one
of it's parents (equal chance) but carries the traits of the other as well
which may show up in it's own children. If a planetouched mates with a normal
creature, there is a chance that creature will come up plane-touched, but
even if it does not, it carries the traits and may pass them down in
generations. Most planetouched will be no more than 1/8th outsider, with
1/16th being the most common.
* Planetouched characters are subject to an ECL adjustment
Unless a planetouched character's traits are overtly obvious or they have
made it known, you should not roleplay as automatically knowing their
race/heritage. Rather they are just odd looking humans. One should also
consider whether they have a mask, hood, or armour that would further obscure
their features.