The closest thing I've ever found to a serious citation on that statement is a White Supremacist website.
You got anything else?
The trick is critters have livers, lungs, muscles, intestines, blood vessels, hearts, brains ~ etc. Lot of commonality out there.
They do not, in general, have substantially different genes building those standard organs.
So, why did you go to a "white supremacist" website to study biological science?