Is there woman really?

I'm taking a class about language. This is the class for English learner. But most of my classmates are returnee mostly from United States. Only 3 people in the class, are born and educated in Japan. And we have discussion in English , this is passion for me!! I read article every week, and discuss about that. It's challenging every time , I am sure it will help improve my English ability.
Today , we discussed about gender and language. written by Cameron. Main point of the article was that there is no definite gender, there is no really woman or man. Gender is socially constructed. That is clear with the example of gay and lesbian and bisexual. Biological sex exists,but gender socially constructed does not exist. Every one has different ideal of gender. And social ideal gender is changing. For example ,　草食系男子 , or vegetable men.
It is interesting what makes better image of gender, I mean , for example ,ideal character of salesman exists, that has feminine character , interpersonal skills, communication skills which are more distinctive character of women, because women acquired this in order to survive while men hunt animal or go to war. So salesperson tend to use woman-like language. But it is interesting that how do they know woman-language while they have not learned before.
The function of brain is wonderful!! How flexible it is!! Why do billions of neurons makes this wonderful function?
Anyway, today's discussion gave me new insight toward things. Not only gender, a lot of things don't have definition. I am keep going