There's a gem of truth in what you say: culture is probably the largest factor in behavior differences/outcome differences. Sometimes because one culture has different setpoints for accuracy/reliability/punctuality for instance, that would make members more/less appropriate for some occupations.

But sometimes its just that one culture currently dominates a social/economic niche for historical reasons. Then members of other cultures have a hard time 'fitting in'; they can't catch a break because they don't know anybody in the industry and may even seem strange/uncomfortable for those in power, so get excluded or overlooked as new members.

Your Hollywood example may fit in that camp I believe. Maybe Jewish culture is a superior fit; maybe historically folks from that crowd entered the industry in its infancy and the rest is cultural momentum. For better or for worse.

The lesson for Silicon Valley and its bro-culture is then clearer. Why no women? Because in the 50's, there were few women. And if there is a 'women's culture', its dissimilar enough from the bro-culture that they feel mutually uncomfortable working together.