Actually, it is an older theory that is still widely held by most academics and Finnic migrations from Siberia are backed by genetic, historical, anthropolgical and archaeological evidence. The easiest evidence to look at is the existence of closely related peoples and languages  to the Finns which still exist in Siberia today, liek the Komi people. Swedes do in large part trace alot of origins to the Halstatt Iron Age culture originally from central asia but most Europeans can claim a majority of old Paleolithic and Neolithic ancestry.