There are no "Croatian" genotypes. "Croatian" and "Serbian" is a cultural, not racial issue. In places like Herzegovina, due to forceful conversion to catholicism of Serbs in the 18th century under Maria Thersea, Herzegovina's Croats have last names like Milosevic, Colic, etc. So much for looks, and different last names. As for sounds, Croatians sound just like their Krajina and Herzegovina Serb counterparts.
So, "many" Croatians (how many?) hid Jews but did they hide Serbs as well? What a joke! Before you come back spouting off more historical inaccuracies and biological untruths, please review the name of Ustasha's fasicst Hitler-allied state: Nezavisna Drzava Hrvatska (NDH). Do you realize that nezavisna is a Serb word and that the "correct" Croatian word is neovisna? Did it ever occur to you (probably not) that the very makers of the Croatian Ustasha state did not know "Croatian" language well enough because it's not their language? Because they didn't mint "their" word for it until much later? Don't you think it is almost an irony, a laughable one at that, that the most anti-Serb Croatian creation had a name that started with a Serbian word?