>>280807467
They already looks extremely similar, to the point where nearly everyone first watching/reading confuse them for each other. I think the originally script had yoriichi as Tanjiro's dad but it was changed last minute. People who didn't think they were related missed basic clues implying that they were related, and thus were not surprised to find out that they ended up not being related. Either that, or the writing is at fault for not getting enough people to think that they were related, which it was clearly intending to do. By admitting that you didn't think that Yoriichi was Tanjiro's dad, you are admitting one of two things. Either A) You are not observant enough and missed the writer's attempts at trying to make it seem like they were related (this implies low IQ), or B) you are indirectly faulting the writing and pointing out a flaw with the series because it failed to trick enough people into thinking that they were related despite that being the intention. In either case, either the one who didn't get tricked is at fault, or the one doing the writing of the series is at fault. There are no other ways to look at it.