Of course, the problem is, children are not raised in a vacuum. They learn behaviors, and speech is one behavior that is only learned, not innate. Left in the absence of an example, no child speaks on his own, but only babbles.
The accent that we speak is always learned. We simply do not begin speaking with a Cockney or Aussie accent by choice. We mimic.
And I've yet to hear a child have the gay voice before it became a trope on television, cinema, and internet. As a child, I never encountered a child who evinced a lisp or lilt until adolescence. It would probably be short work for a linguist to establish research controls and prove the point, but to what end? Again, society isn't going to reward such research and gay men themselves are prejudiced on the subject.
It isn't troubling to consider that there may be multiple origins for homosexuality, but it is damaging to suggest that gays are inherently effeminate. Some are feminine, and some are not. The club is not exclusive.
Read my -osts again. I did not say gays are feminine; many, I think most, are not. But some seem clearly to be inherently. i.e. physically, feminine and would like not to be.

