In childhood, gender is clear but larity is not apparent.

At puberty, a child will either Establish as a Gen and begin producing selyn, or changeover, becoming Sime. Only in the year 232 Unity does it begin to become possible to distinguish Sime from Gen before birth, though prior to that the channel's prenatal selyn draw tended to identify them, though not reliably. 

(Source:  Index card file.  "Childhood" --- House of Zeor

Hugh's point of view and opinion ---  Children in-Territory had seen the madness of Need, the Kill, the overwhelming strength of the sime.  Neighbors, parents, siblings, schoolmates would consider those who had established a Choice Kill (notice Hugh's lack of understanding.)

Out-Territory ---  Hunted, despised, hated by relatives and friends --- adolescents beaten to death by loved ones --- parents' love warped by the fear the child would change over while they slept and attack them --- kids not allowed hammers, nails, knives, or other dangerous tools.

"Thrino" accepts that she has no name because she is a Gen and sticks to the hatred of the perverted Householders (for awhile at least).  Self-hatred.  Not even a "little girl" any more, but a Gen.

(Source:  Index card file.  "Sime~Gen Differentiation" --- Jacqueline Lichtenberg to Michael Amsden --- January , 1976)  GENETICS:  The children of two Gens have a 1/3 chance of being sime.  That's not 1/3 of fertilized zygotes, but 1/3 of those that survive puberty.  Infant and child death endemic; prenatal deaths, abortions very high --- the mutations are still evolving and there are a lot of unsuccessful recessives.  Likewise, children of two simes have about 1/3 chance of being Gen.

Does not hold as much for Farrises, who tend to be Sime, mostly channels.  The few Farris Gens are terrific Donors.