You can push for diversity all you want, but what if that's just not how people behave? Again watch the documentary I think Norwegian society is a far better a case study for Gender issues than anywhere else on the planet.
Not to mention misrepresenting what "the argument" is about, but I guess you've already moved on from that.
I think you are missing the point of the argument for encouraging diversity. Discrimination is one aspect yes, but there's a lot to be said for encouraging young women to explore these fields just by having a visible number of women in those roles.
To me it would be wildly inconceivable for predisposition to certain jobs to be an inherent biological trait rather than something shaped by society.
Doesn't really matter what would inconceivable to you. What matters if that's the reality of the situation. Watch the documentary it addresses it.
No. I'm saying we don't know whether the current representation is the "most natural", but what if it is?
Furthermore if you had looked through the video you would have realized that the entire basis of the documentary is an attempt to answer why labor force participation often becomes gender segregated. You say that it's because of lack of "encouragement", but maybe there's something else at play.
This same comment is made every single time there's a discussion of gender equality in tech, and when examined betrays the entire "anti gender equality" narrative.
People are in fact pushing for women in every single one of the fields you mentioned:
Construction: http://www.nawic.org/nawic/NFSFScholarships.asp
Plumbing: https://www.aspe.org/WOA
Welding: https://app.aws.org/foundation/scholarships/air_products
The next point that's brought up is "well then why aren't people pushing for more men in female dominated industries." To which the answer is, they are, and have been for a long time: http://www.aamn.org/about-us/scholarships
It seems fishy to me when people are willing to speak out against diversity in tech without bothering to research any part of their argument.