It really helps to look at things at a biological level.
1) Marriage and a couple raising their children is a superior way to raise children. It benefits the husband, the wife, and especially the children. It is far better than just monogamy.
2) If children are to be raised in such a way that they can develop a healthy relationship with their spouse, they must be raised in a mixed gender environment. Every element of their life, except for private times, needs the opposite gender there and interactive with them in a chaperoned manner.
Children with several siblings who are of the opposite gender usually have much better relations with those of the opposite gender.
It is devastating for children who are raised in gender isolation, only exposed to children of the opposite gender in circumstances where they are kept too busy to interact. Then, at the age of 17 or 18, they are expected to date, then marry someone they like and have children in a stable environment. It’s not going to happen.
You might as well invite them into an operating theater during open heart surgery, then ask them to “finish up and close”. It’s not going to happen in such a way that the patient lives.
Your studious avoidance of the word "sex." That word is a neutral, central and necessary descriptive within all of biology. Sex is a descriptive of most living things; "gender" is a quality of words.
A real professional, unburdened examination of what I thought you were attempting, is the excellent 1997 book, Sex on the Brain, by Deborah Blum. I deem the title sadly misleading; snowflakes of all ages may deem it suggestive.
It is a serious book, professionally written, highly informative and thought provoking.