Croats do have a substantial amount of genetic influence from a polish/russian like source. Croats from all balkan slavs still have a massive amount of polish type dna, probably around 50%. Croats do not cluster with albanians and greeks who most people would consider as more unmixed balkan natives. Pca plots are not the best representation of genetic relatedness. Me and my american grandmother are light years away from each other on a PCA plot yet are more closely related than anyone besides my immediate family. Its already been proven that eastern europeans share more IBD strands with eachother than western europeans do so again we cant take pca plots at point blank. Croatians have significant slavic ancestry whatever definition people use, it would be totally incorrect to say they arent slavs genetically.
Sent from my KIW-L21 using Tapatalk