Repugnance
Men feel repugnance when they see or imagine their mother or sister naked.
Men feel the negative effect of repugnance when they feel visual pleasure from a woman they lived with when they were 2-6 years old. The stronger the visual pleasure a man feels, the stronger the repugnance he feels. Walking in on a naked mother or sister makes a man feel the strongest repugnance.
You can see evidence of repugnance when girls with brothers date other boys. Brothers are uncomfortable with their sisters dating. They know other boys want to have sex with their sisters. And imagining that possibility makes brothers feel repugnance.
Women do not feel repugnance.
Although women do feel sexual pleasure like men, they do not feel repugnance. Evidence of the difference can be seen in the differing attitudes of siblings towards dating. Boys are clearly uncomfortable with other boys dating their sisters, but girls are completely comfortable with others girls dating their brothers. They even act as matchmaker setting up their friends with their brothers.
Fathers do not feel repugnance towards their daughters.
We assume that fathers feel repugnance towards daughters because it would prevent incest. However, they don't. In the distant past, fathers did not grow up with their daughters. They moved on to a new woman long before their children reached puberty. So there was no need for men to feel repugnance towards their daughters.
This is real problem today - fathers are now typically with their daughters when daughters reach puberty. Fathers, mothers and daughters need to be aware of the risk. Fathers should not be alone with daughters. Fathers should not be overly touchy with daughters. Mothers should monitor the father and the daughter for inappropriate behavior. Daughters should dress conservatively around their fathers.
Daughters will be tempted to attract their father's attention. Daughters do not feel repugnance either. Although daughters cannot become infatuated with their fathers, fathers can make their daughters feel pride by giving them more attention.
Boys do not feel repugnance towards much younger sisters.
Specifically, boys don't feel repugnance towards sisters that are 7 or more years younger.
We assume that boys feel repugnance towards sisters of any age because it would prevent incest. However, they don't feel repugnance for sisters born after the boys were 6 years old. In the distant past, brothers did not grow up with much younger sisters. Brothers left their families looking for a mate before their much younger sisters reached puberty. So there was no need for boys to feel repugnance towards much younger sisters.
This could be a problem today - but only if an adult son is still living at home when his much younger sister reaches puberty. There would be a problem, for example, if a 23 year old son is living at home with his 16 year old sister. Repugnance will not discourage him from being sexually attracted to her.
Repugnance is only caused by incestuous behavior.
Repugnance is not caused, for example, by homosexuality or masturbation. Although these behaviors do not lead to reproduction, they do not cause significant harm either - like incest can. Homosexuality and masturbation waste a little time and semen, but that's it. Incest can waste of months of gestation and years of parental support. Repugnance evolved to deter the substantial harm caused by incest but nothing more.
Men feel the negative effect of repugnance when they feel visual pleasure from a woman they lived with when they were 2-6 years old. The stronger the visual pleasure a man feels, the stronger the repugnance he feels. Walking in on a naked mother or sister makes a man feel the strongest repugnance.
You can see evidence of repugnance when girls with brothers date other boys. Brothers are uncomfortable with their sisters dating. They know other boys want to have sex with their sisters. And imagining that possibility makes brothers feel repugnance.
Women do not feel repugnance.
Although women do feel sexual pleasure like men, they do not feel repugnance. Evidence of the difference can be seen in the differing attitudes of siblings towards dating. Boys are clearly uncomfortable with other boys dating their sisters, but girls are completely comfortable with others girls dating their brothers. They even act as matchmaker setting up their friends with their brothers.
Fathers do not feel repugnance towards their daughters.
We assume that fathers feel repugnance towards daughters because it would prevent incest. However, they don't. In the distant past, fathers did not grow up with their daughters. They moved on to a new woman long before their children reached puberty. So there was no need for men to feel repugnance towards their daughters.
This is real problem today - fathers are now typically with their daughters when daughters reach puberty. Fathers, mothers and daughters need to be aware of the risk. Fathers should not be alone with daughters. Fathers should not be overly touchy with daughters. Mothers should monitor the father and the daughter for inappropriate behavior. Daughters should dress conservatively around their fathers.
Daughters will be tempted to attract their father's attention. Daughters do not feel repugnance either. Although daughters cannot become infatuated with their fathers, fathers can make their daughters feel pride by giving them more attention.
Boys do not feel repugnance towards much younger sisters.
Specifically, boys don't feel repugnance towards sisters that are 7 or more years younger.
We assume that boys feel repugnance towards sisters of any age because it would prevent incest. However, they don't feel repugnance for sisters born after the boys were 6 years old. In the distant past, brothers did not grow up with much younger sisters. Brothers left their families looking for a mate before their much younger sisters reached puberty. So there was no need for boys to feel repugnance towards much younger sisters.
This could be a problem today - but only if an adult son is still living at home when his much younger sister reaches puberty. There would be a problem, for example, if a 23 year old son is living at home with his 16 year old sister. Repugnance will not discourage him from being sexually attracted to her.
Repugnance is only caused by incestuous behavior.
Repugnance is not caused, for example, by homosexuality or masturbation. Although these behaviors do not lead to reproduction, they do not cause significant harm either - like incest can. Homosexuality and masturbation waste a little time and semen, but that's it. Incest can waste of months of gestation and years of parental support. Repugnance evolved to deter the substantial harm caused by incest but nothing more.
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