While talking with Kassandra, Kahn came to realize how similar their situations were after Kassandra started expressing her pain and suffering little by little.
In his life as Elric… It wasn't like he never tried to appease his parents or gain their recognition. He was born with a weak body and hence had many disadvantages when it came to sports or any athletics.
There were times when he used made the best use of his eidetic memory and topped in school competitions. But what use was it if your family didn't even bother to come to cheer you up?
He was like an unwanted child born out of mistake to his parents.
Hence, as Elric grew up, he never had real motivation or urge to excel in these fields. Because no matter what he did whether it was sports or academics… it was never enough for them. The standards his parents set for him were too high.