The name is Trotsky and he grew up secular in a secular farming community.
The story usually told is that he wanted to go to Cheder but they were unwilling to take him in. Based on his completely secular upbringing it is very unlikely to be true. I’m sure he spoke no Yiddish and that the ONLY language most frum people spoke back then so how could he have gone to a Yeshiva.
However, on a different note, Bernie Sanders went to a frum run Sunday school. He was completely uninterested, his mother was upset that his father insisted he attend and even his father only kept Yom Kippur and made a Seder with neighbors (apparently he and his mother didn’t attend)As such there was a next to no chance that the Sunday school he went could have had any influence on him. Even so, I still had only they realized who they were dealing with they would have made so much more effort to influence him. With any child, you never know who you are dealing with