Do I really need to explain this to anyone from Balkans?
Croats and Serbs are two nations that organically developed from the same root since early Middle ages. Bosniacs are artificial nation same as Montenegrins, albeit bit older than Bosniacs.
Until 90-ies civil war Bosnia was always just a territory inhabited by Serbs and Croats some of which converted to Islam.
Montenegrin national identity at large was historically that of Serbs living in a separate state.
Makes sense?
Thanks.
Things might not be so simple as you presented them, as for example Croatian national identity is a rather vague and dubious term historically speaking until the Turks were pushed away eastwards to and across river Drina by the Habsburgs and other Western powers, and the rise of national sentiments in Europe in XVIII and especially in XIX century for the Balkans. Haven't properly studied the Serbian part so can't say much or reliable things about historical basis for their national identity.
In that respect, it was the Montenegrins, who in fact didn't consider themselves as a part of the Serbian nation, who rised up first against the Turks in regions still under Ottoman rule, but were basically backstabbed by the Habsburgs who had different plans than to let some Slavic 'nation' be independent on the teritory in their projected sphere of influence.
In that sense, very similarly to what was done to Galicia and later Ukraine, Habsburgs organized 'controlled' national awakening in the Balkans as well, with Vuk Karadžić coming fresh from Vienna with first panslavic and then so called Illyric movement ideas, substituting the Old Church Slavonic as only commonly understood language of the peoples in the region with a more or less obscure dialect from mountainous area between today Eastern Herzegowina and Montenegro. That chosen dialect became the standard upon which Croatian and Serbian languages as we know them today were based. He also changed the Old Church Slavonic cyrillic script to what is now used as Serbian cyrillic script for example. All these things that transpired in those times vis-a-vis creation of national identities of Slavic peoples especially under the Habsburg dominance can be regarded as a sort of 'balkanization' of the Slavs, or at least Southern Slavs, removing them basically from Mother Slavic or Russian influence and breaking them into smaller and easier controllable pieces through local corrupted newly established elites, who were rather easily instigated to be at each other throats.
The Muslims were unofficially introduced as a separate nation in 1974 with new and AFAIK last Yugoslav constitution, when then already old and removed from reality on the ground in his own country of origin Tito was de facto pushed to do that after so called Croatian spring which was effectively what we would call now color revolution of sorts, just on a 'local' scale. That constitution was also the legal basis upon which the real Balkanization could be performed cca 20 years later, when as you said Muslims became officially Bosniacs. With the 1974 constitution many of them declared Yugoslav nationality, newly officially established category, neither as Serbs nor as Croats who were more often than not referred to as Orthodox and Catholics before the turmoil of the 1990s.
Well, it was not the historical part as such that was of interest in the question, but if there are, to your knowledge, some real differences, like genetic or some other, that actually distinguish Croats from Serbs, that are not found also in Bosniacs and Montenegrins. For example, you said that Albanians, although they consider themselves to be descendants of original Illyrians and not really Slavs, have actually the smallest amount or concentration of this so called Illyrian gene.
Is there something like that which could play the role of discriminator function for other Slavic 'nations' in the Balkans?
Apologies for not making myself clear with the original questions in the first place, and for obviously annoying you.
