I am male who went to a single sex school. I didn’t really enjoy the fact boys were mean because I was not the most normal kid. I would have preferred going to a mixed school and tried to make friends with girls but people kept on saying that girls were “bitchy” and could be more vicious than boys?
Is this really true and if so what’s the cause? Is it socializing, genetic, or a mixture of both?
I didn’t notice the girls being meaner, as a group, than the boys. Mean girls were certainly common enough. But at least in my memory, they were the minority.
Mean girls tend to direct their meanness towards other girls. So I think your maleness would have protected you from their wrath.
I have a theory that in general women don’t like other women as much as men like other men.
What you have, is a hypothesis.
Well, technically, a half assed feeling 
Speaking as a former schoolgirl who attended only coeducational schools from kindergarten on up, I didn’t notice a significant difference in average niceness/meanness levels by gender.
I think there are at least two major confounding factors in the traditional “girls are bitchy” assertion:
Girls and boys may be equally likely to say and do unkind or unpleasant things, but only in girls is such behavior called “bitchiness” instead of “meanness” or “aggression” or another less gendered term.
Traditional social gender roles condition us to expect girls to be more deferential/cooperative/affectionate etc. than boys. So the same not-very-nice action can be perceived as “normal” for a boy but “bitchy” for a girl.
Admittedly what follows is random speculation without anything other than possibly stereotypes to back it up.
Bullies exist at that age among both sexes as the desire to gain status and self esteem by pushing down others is universal. But boys are more likely to bully others around them with physical aggression while girls are more likely to do so with social aggression.
In my (entirely anecdotal, of course) experience with a coed environment, boys are more likely to get in each other’s faces, and girls are more likely to get catty behind each other’s backs.
This does not mean that girls never throw punches or boys never spread rumours, of course - merely that there is some level of observed preference with regards to bullying techniques.
I think that Buck Godot is closer on this one. Boys are expected to assert themselves physically, establish the pecking order, (backed up by violence), and then move on while girls, “denied” the physical aggression, (in many situations), resort to prolonged verbal antagonism. (Boys continue the insults even after the pecking order is established, but once established, the insults tend to follow a set pattern of name-calling or repeated references to similar jokes.)
I don’t think so. Males and females tend to display aggression differently. This even carries over to adulthood. I have been in number of shops where women will say that they would rather work with men than women because the work climate among men is less vitriolic or caustic. Possibly due to the threat of physical violence, (and workplace rules prohibiting it), men do not appear to engage in as many “catty” exchanges as women.
This is not a claim that men all get along and women all fight. It is an observation that the manner of displaying antipathy tends to differ between men and women. Men are quite capable of behaving obnoxiously and expressing contempt or disdain for fellow workers, but it is expressed differently.
That may be true without actually contradicting or rebutting anything I said. Even if it is, it may well also be true that exactly the same behavior or remark would typically be considered “no-nonsense”, “assertive”, “candid”, “confident”, “witty”, etc. in a man, but considered “bitchy”, “vitriolic”, “caustic”, etc. in a woman.
In other words, it’s not just about different styles of “displaying antipathy”; it’s about the possibility that what comes across as “antipathy” when expressed by a woman is more likely to be interpreted simply as “assertiveness”, “self-confidence”, or some other positive or neutral quality when expressed by a man.
Citing a single study of course doesn’t conclusively prove anything about people in general, but here’s a description of one study about different reactions to the exact same facts/behavior presented under different gender identities:
(Emphasis added.) See? Exactly the same behavior and personality is perceived as acceptable and normal when the person in question is believed to be male, but unpleasant and dislikable—in other words, “bitchy”—when the person is believed to be female.
So it’s not just that “males and females tend to display aggression differently”: it’s that women tend to be held to stricter standards than men when it comes to criticizing them for perceived “aggressiveness”.
Without drawing any specific conclusions on the topic, I offer the following efforts to analyze the topic:
Gender Differences in Subtypes of Workplace Aggression
I will refrain from claiming the following to support my position:
Women are ‘Bitchier’ than Men, a Non-Experimental Study Says
Again, all that such studies show is that women are more likely than men to be perceived as engaging in “bitchy” behavior.
They don’t address the question of whether a particular behavior is more likely to be perceived as “bitchy” when women engage in it as opposed to whether men engage in it.
In other words, it might be that women tend to be objectively “bitchier” than men. Or it might be that women tend to be perceived as “bitchy” for the same types of behavior that are taken for granted as “normal” or “appropriate” in men. Or it might be some combination of the two.
I have noticed that boys can go in and out of being friends and enemies with each other. Put them on the same sports team though and they become good friends again.
However with girls I’ve found once they hate another girl they never get over it including into adulthood.
Boys (I used to be one) settle matters with their fists. Girls (I have three daughters) tend to prefer character assassination, unless a boy is involve then he suffers at the hands of the sisterhood (painful)
I’m confused as to which of these behaviors is being put forward as more “bitchy”. ISTM that you could have meant this in one of two different ways, more or less as follows:
A. Boys tend to be more petty and offense-prone, quarreling over things that don’t really matter to them and reconciling for equally superficial reasons. Whereas girls tend to be more steady and loyal in their affections unless and until they hit a genuinely irreconcilable difference, at which point they cut their losses and never look back.
B. Boys tend to be more robust and easy-going, accepting cycles of friendship and enmity as part of natural give and take. Whereas girls tend to be more brittle and vindictive, incapable of recovering from even minor conflicts.
In the first interpretation it would seem that you’re describing the boys’ behavior as more “bitchy”, while in the second interpretation it would be the girls. Which did you mean? (Or something else entirely?)
My own theory - or hypothesis, if you prefer 
- is that women are in general more relationship-oriented and focused on social interactions and standing than men. So that when in any sort of relationship or social scene they are more focued on that relationship or social scene than men in a comparable position.
The result of this is the heightened sensitivity to real and perceived slights and increased jockeying for position that many people (both male and female) perceive as “bitchiness”, in a variety of social situations.
For a prior thread on a related topic: Lesbian Civil Unions Breaking Up at Nearly Twice the Gay Rate
Perhaps related.
My “hypothesis” is that men compete with other men. Women see other women as competition.
Add the numerous disclaimers here…
? What “matter” is being “settled” when mean boys beat up weaker boys just for fun?
ISTM that this is another example of subtle “erasure of bitchiness” in descriptions of boy behavior.
The implication is that physical aggression between boys is typically just an honest and mutual “settling of matters”, whereas in reality it’s often just one boy bullying another for no good reason. That behavior would be called “bitchy” if girls were engaging in it.
Anecdotally, as a little girl, I was a little on the weird side and I was not popular. But the only kids who ever teased me (and I’m talking kindergarten through high school here) were boys. And no, they didn’t secretly like me, they just had fun teasing me. I’d call that “bitchy”. YMMV.
As an adult, I’ve enjoyed working with both men and women. However, I think the best workplaces are mixed (and I think there are studies to back me up on that, but I’m too tired to look them up). I worked in one situation where it was a large group of women, and there was some occasional catty behavior. I’ve also been in situations where it was more male-dominated and there was a lot of boasting going on that I found not at all pleasant. Environments where both genders are present have, in my experience, been productive and generally happy places to be. Again, YMMV.