like i said. just associations you have lived and been taught. Things you believe because they seem so.
You cant prove the specific biological mechanisims. You can't eliminate more plausible reasons. You dont understand the details, not because your dumb, but the because stories fail under close scrutiny.
And your taught not to question, not really question. So you dont, you accept and these are just beliefs you have. And good for you. I require a little more evidence before I hand over my body or my children.