The key to this . . .
. . . is the "fantasy"
In my somewhat limited but oh so joyous experience, most, if not all, of what happens between an SP (or even several SPs!!) and a client involves some element of fantasy.
If the mother/daughter (and yes, jessi, father/son) scene would turn one's crank, who are we as regular and, I will admit, somewhat perverted TERBites to judge?
Personally I'm intimately aware of at least one MILF and one sweet, petite young (but legal!!) lady on this board who'd make a terrific mother/daughter combo, could I afford it and if, of course, would they agree.
I certainly understand the ewwwwww . . . . factor in this but, if you're going to play on TERB, be prepared to be surprised!!!
Just MHO!!!