This is Weronika Książkiewicz. She is considered “Polish actress” due to living in Poland most of her life, having Polish citizenship and having one Polish parent (father is Russian and she was born in Moscow), but according to this interview, for example: http://polki.pl/zycie_gwiazd_znaniilubiani_artykul,10009228.html, she makes it perfectly clear she is half-Russian and half-Polish. She speaks perfect Polish and very little Russian. Is she Russian?

Here is another such example:


This is Beata Sadowska. She is considered “Polish presenter” due to living in Poland her whole life, being born there, speaking only Polish, obviously having Polish citizenship, yet her paternal grandfather was Chinese (therefore, this is her paternal line and she is 1/4 Chinese and 3/4 Polish, 100% from maternal line and 50% from paternal grandmother line). Is she Chinese?

First one is 100% Slav (Russian/Polish) and second one is mongrel pup with predominant Slavic origins. Neither are considered Russian or Chinese.
So no, this whole story of “Slavic tradition” makes no sense to me and it’s no wonder I have never heard about it in Poland.