Ever since we got to know Shoto Todoroki's character, we've found that his relationship with the family isn't all roses and flowers, quite the opposite. During the arc of My Hero Academia with the sports festival tournament, the boy was at the center of some dilemmas caused by his father, Endeavor, who was guilty of his being obsessed with overcoming All Might.
These Endeavor's dilemmas have deep roots in My Hero Academia and the final chapters of the manga deal with the Todoroki family's past due to the discovery of Dabi's true identity. When Rei and the kids arrived at the hospital to speak to the flamboyant hero, they began to come to terms with their family's past and remembered the moments when Touya was still with them.
After Endeavor tries to prevent Touya from using his flames again, he decides to have children until the perfect one arrives, so that the firstborn surrender. With Shoto he succeeded and for that Endeavor has trained him hard since childhood. At the same time, however, Shoto wanted to play with his brothers, while Touya viewed with contempt and desperation the new situation that had arisen. The moment Touya attacked Shoto was when Endeavor's obsession peaked complete separation of the last todoroki from the other family members.
Yes Links to other events already told in My Hero Academia which Kohei Horikoshi is now investigating further.