If you have not read my previous blog post, under the name of Dabi Todoroki?, I recommend you do so, as it may explain more about what I am suggesting.
There is the fact that (although this is not hereditary) Dabi and Endeavor have similar features. Dabi has scars below his eyes and upper lip, while Endeavors has fire around his eyes and mouth.
Also, there is a theory that Dabi is “sensitive to heat”. In the manga, it is shown that Dabi bleeds where his burnt skin meet his healthy skin. This may be because his quirk harms him (similar to Izuku, but perhaps more permanent or it may have not been treated correctly).
This blog post was not created to change anyone’s opinion or to offend anyone. It was created just for fun and to entertain others about theories.