If we eliminated all those whose genes turned Polish out of conformism (helped with a lot of fear, despite what Polish propaganda says), how many szlachta would be left?
Several hundreds of thousands.
Not much in a nation of 40 million.
In the sense that they were Lithuanian, and Orthodox, specifically spoke Lithuanian and/or was descended from Lithuanian tribes and was baptized Orthodox. Even most of the first generation of the Jagellions after Krewo/Kreva remained Orthodox and did not apostatize with him.
No Lithuanian tribes were baptised Orthodox and almost no
Orthodox spoke Lithuanian then. Lithuanians (or, more precisely, Lietuvises) were pagans.[/quote]
Vaišelga, son and successor of King Mindaugas as Grand Duke of Lithuania certainly spoke Lithuaninian, was descended from Lithuanians tribesmen (most Lithuanians are: their genetics show the population has been pretty stable ever since settled), and was baptized Orthodox. I'd have to look up again, but their were areas when Orthodoxy had begun to penetrate. Most, however, perhaps came from intermarriage with Orthodox Rus', as the case of the Jagellions, all of which spoke Lithuanian, were descendants of Lithuanian tribesmen, and were baptized Orthodox. The last Jagiellon to speak Lithuanian was Alexander (Aleksandras Jogailaitis), Grand Duke of Lithuania from 1492, and King of Poland from 1501, until 1506. He was also (coincidence?) the last to marry an Orthodox, Helena of Moscow, heiress of the Rurikids and the Palaiologans. The Olelkaičiai, among the last Great Princes of Kiev, were descendants of the Lithuanian tribes-being the scions of Algirdas, Grand Duke of Lithuania, as was Teodoros/Fyodor of Kiev, brother of Gediminas, the Grand Duke of Lithuania and the founder of its state. All were Orthodox descendents of Lithuanian tribesmen-whether they spoke Lithuanian in Kiev I don't know, but their relationship to the rulers in Vilnius suggests yes. There were many such families, which, if they remained Orthodox, mostly ended up assimilated into the Rus' population-some going to Moscow as the Crown insisted on its Latin faith in the Commonwealth.
Majority of the GDL inhabitants were Orthodox Ruthenians.
That would be a given. The ratio of Ukrainians (38 million) and Belarussians (9 million) versus Lithuanians (3 millions) in the area of the GDL today doesn't seem to be very different from what it was, which couldn't have been more than 10% Lithuanians in the Grand Duchy at its height.