In classic scientific method you propose a theory which lead to testable predictions. Gravity is a force that pull objects towards each other, this predict behavior and experimental tests validates it.

If men created gender roles and gender expectations then a few predictions should be made, so I will state three. 1) During war women should be drafted into the military and put in the fire line before men. 2) gender roles should change during historical time when a queens hold power. 3) as creator of gender roles they should be able to change gender role as is seen fit.

Through history its common that those in power draft proportional from subjugated groups during war. Slaves, criminals and unwanted was put forward as cannon fodder in many wars, Africans was the majority of the fighting forces during the colonial times and African-Americans were often disproportionately drafted in the US between the period of first word war and Vietnam. Slave labor is also a common theme between the powerful and the subjugated and used in almost every place in the world

An other prediction is that we should expect to see changes when the gender of those in power are changed. The Victorian era is strongly associated with gender roles. The era is named after Queen Victoria's reign and there is nothing to imply that gender roles was somehow reversed during this era. There is no identifiable pattern in history that the gender of those in power has an impact on gender roles.

The third one is rather long story but I will describe a anthropology writing about a famous African tribe that managed to stay fairly isolated and static until the 90s. Children of both sex stayed with their mother until around 10 years, after which they were split into male and female areas. The boys had their genitalia ritualistic cut by the elder men during which if they made any sound they would cast great dishonor on their family. The researchers were not allowed in the female sections but reportedly similar rituals was held by the elder women. After which the boys was group into semi-similar age groups and teached the way of the warrior, ending with a test where they went in alone in the forest without anything except a spear and was only allowed to return if they killed a lion. If they survived the trial they where given the title warrior and a wife that the female elders selected. The warriors then regularly raided every few years with machetes and spears and died usually rather young.

Now setting aside which life was worse, who held power in this culture? Could a man dictate who married who? No. Could a man decide that he was not going to get ritualistic cut or that he choose not to enter the jungle? No. Could a man decide that he did not want to go and raid? No. Could he dictate who married who? No. Similar a woman could not decide to go hunting. A woman could not decide to eat meat. A woman could not decide to not get ritualistic cut. The roles was laid out with almost a literal line in the village between women and men. The elder men held power of the men and the elder women held power over the women.

Then during the 90s a change did happen. The elder men changed the details about what the men in the village would do. A civil war had killed a massive number of the men, and later tourism started to compete as primary source for food. This resulted in a stop in the warrior culture and boys were no longer required to go into the jungle and kill a lion or raid. The elder women also change their side a bit, primarily by putting children of both genders into school. genital mutilation is still common for both genders and it is still the elders that decide who should marry who, but slowly those things are eroding through cultural homogenization.

Which gender held a position of power in that village in the past, and which gender holds one today? A major part of gender roles is that they split power along gender lines where crossing them is forbidden. Taking a historical perspective, the feminist movement spearheaded the movement to abolish gender roles but it sadly gave up on those around the 70s and is today more focused on who holds positions of power. This has resulted in very little progress to eliminate gender roles in the last 50 years. "Men rights" movement is both young and split with parts that is competing with the feminist movement about positions of power and the other that tries to take up torch against gender roles which the feminist movement abandoned. Examples of the later is those that fight for more women in the military, equal rights for adoption (and the right to start a family), the elimination of alimony and child support, and gender neutral efforts to reduce gender segregation.

> What's your working theory?

The two cores in gender roles is that women raise families and men support the raising of families. We see this in dating and in studies of inter-sex competition. A prediction of this is that we see exaggerated gender role behavior when a individual is among their own gender. Since it is about social rank we should expect to see the behavior starting at very early age and much earlier than puberty. Dating statics also show a identical correlation along those gender roles, where male success is about showing how they can support the raising of families (job, wealth) and female success is about showing how they can raise a family (hip size and so on). If we want to stop those gender expectations then we have to eliminate those gender roles, and I would predict it would cause a huge change for gender segregation in the work market.