Stalin had an affair with a 13 year old girl when he was in his 30s
After returning from his first exile, Stalin persuaded to attend a fundraising ball thrown by the group that eventually became the Russian communist party. However, the ball was raided by the Okhrana (a Rusian security force) and Stalin was exiled once again to Siberia. His sentence was to spend 4 years in exile. After moving him around due to escape plans, he was moved to the northern town of Kureika.
Kureika is in the Arctic Circle so Stalin was really out in the boondocks of the USSR. While living in Kureika, Stalin became a hunter-gatherer after learning from the local Serbians. That's not all he picked up from the local Serbians. While he was in exile, the 30-something began a two year affair with a 13 year old named Lidia Pereprygina. She became pregnant twice by Stalin. The first child died as an infant, and the second one was born in April 1917 and named Alexander