This sounds like Sunwaifs, a novel by Sydney J. Van Scyoc from 1981, which deals with the colonization of a planet called "Destiny".
From a summary on Goodreads:
Nadd is our first narrator and he begins by telling us about how he
worries for the new generation. He recounts the hardships the original
colonists had to endure their first years on Destiny--a planet that
had seemed at first so perfect, but quickly proved itself to be
anything but. His intentions is to leave a logbook for the next
generations so that they may be able to avert the disaster he sees
brewing. To this end he asks an... aquaintence of his for help in
writing the log book. I hesitate to call them friends, or companions,
because in truth the six original 'Sunwaifs' aren't really.
Each original Sunwaif has an extraordinary gift, bestowed upon them
while in the womb by the radiation of Destiny's sun. This both saved
them and cursed them, marking them as different in a world of dogmatic
people who had given up hope and nutured their bitter, hard lives.
As the story unfolds we meet the other four Sunwaifs--Feliss, Trebble,
Ronna and Herrol--and watch as each matures and wants different
things. But always are they connected, by a bond they can't break no
The "sunwaifs" were the first generation of the colonists' children to survive. Three are indeed male, two female, and one is neither (or both).
The book is available for free loan from the Internet Archive.