I believe that when a person takes DNA from an object that someone else has touched and then deposits it onto a third surface then this is not 'secondary' but 'tertiary' transfer. This is what you are suggesting. Secondary transfer would be a hand shake etc then deposit onto another surface. Tertiary transfer is someone touches a door handle, then another person touches the same door handle and then deposits some of the DNA onto another surface they touch subsequently. In laboratory conditions, it was not considered a viable way to contaminate DNA, but here you are suggesting that PR went from the Whites (who were all DNA tested I believe) to the Walkers and the Steins (again we assume all these were DNA tested) and at some time she touched a surface that an unknown person had also touched, came home and when putting longjohns on her daughter, deposited this foreign DNA from her hands onto several places on her daughter's clothing and underwear? Hmmmm a likely story!
I am not so sure those people were all tested. There used to be a page on that on ACR, I'll try to find it if it still there.
One thing I am sure of- no male CHILDREN who were there were ever tested.
And they should be tested now. None of them can be compelled to do this, and I doubt any would volunteer. But I can't stress enough how erroneous it is to look at the male DNA as being exclusively ADULT male. JB was around male children all day.