Inspired by some past prompts. Finn's parents are senators in the New Republic and close friends with Leia. When Leia realizes that there are some people who want her child (Snoke, TFO or even NR thinking he could be a threat), she asks them to take her son and raise him in secret until it's safe for him again (it worked for her and Luke).

Bonus + The First Order comes after them and that's how Finn is taken. When Kylo is old enough and learns their child was taken while they protected him, he tries to rescue Finn. Maybe he meets Rey and Poe along the way.
++ Like his mom Kylo ends up as a senator for The New Republic.