what does distortion achieve in Franz Kafka's The Metamorphosis?

Question

especially in terms of gregor's relationship with his family.

Answer 1

Kafka was a schizophrenic. This idea of a man becoming an insect can be seen in delusions. He also mentioned in other stories an ape becoming a man. Don't try to explain Kafka in rational terms.
The idea of the insect might reflect the alienation that the schizophrenic patient feels when he realizes that the environment is different ( or that is what he feels )

Answer 2

I've never heard that Kafka was schizophrenic! I've read at least two biographies on him and a long, well-reasoned letter he wrote later in life to his abusive father as well as all of his short stories. Kafka was far from mentally well but he was not delusional. The Penal Colony (one of his short stories) has a very cruel logic to it as does the metamorphosis in its own way. As for the distortion, ask yourself what is more odd, him turning into an insect or his persistent concern about getting to work on time in spite of being an insect?