Average liberal: Your preferences and tendencies are just what they are because you grew up in a certain social environment! If you’d grown up in Ghana or Thailand, they’d be totally different!
Average non-doof: Ok, what is your point here, exactly? That if everything had been completely different than it was, they’d be completely different? Brilliant. I commend your perspicacity.
(While there are some valid arguments around the Rawlsian veil of ignorance and the universal lot of humanity and the commonality therein, the average liberal is not making this argument and probably does not know who John Rawls even is; rather, they just want to give your shit and your country to some third-worlder because they “deserve” it more than you do.)