just pretend this is green
Easy, just look for twins in the Bible belt.
Utah & Idaho too. Don’t forget about the Mormons.
Mormons would be the most likely to actually engage in this behaviour since their religion actually promotes it.
EDIT: Sorry mormons.
Incest? Mormons don’t promote incest. Polygamy, absolutely, incest, no. White Mormons do tend to be more closely related than normal, but certainly not close enough to cause any issues. My parents are 9th cousins.
There was a story circulating a few years ago about a pair of twins who strive to be “the most identical twins in the world”, which includes sharing a fiancé and timing their pregnancies for the same date. It is not mentioned whether they bang each other though (not something I care to speculate about lol).
I suppose the first step to making the OP’s fantasy possible would be having massive amounts of money.
The sex doesn’t even sound like fun. After a few months, I’d probably end up looking just like their dad
