All might

so your nana shimura's son/daughter and The pro heroes (Aizawa,Vlad king,midnight,all might,hawks,nezu,best jeanist,Endeavor,Edge shot,present mic,cementoss,Mirko,Sir nighteye,Mt.lady,Kamui,Pixie,gran torino,tensei,recovery girl,manual,death arms,Mandalay,thirteen,Pixie-bob,Ragdoll,tiger and ryuko) have kept it a secret from you for 12 years (Your 12 years old)