Los X son muy suyos y se creen el ombligo del mundo

Los X son muy suyos y se creen el ombligo del mundo
 

Ser muy suyo = recelar del prójimo
creerse el ombligo del mundo = creerse los mejores del mundo

In ENglish?

Be very wary of his neighbor = navel of the world believe = believe the best in the world

this is just a guess. :P

I don't think it's right though. I used the Translator

The machine doesn't translate idiomatic expressions, which is what these are.

creerse el ombligo del mundo

ser muy suyo
= To keep to oneself. (to be reserved, to be introverted)
= To be a character. (meaning such a person is hard to figure out - usually said, "What a character.")
= That's just like him/her. (strange/reserved behavior is characteristic of the person)
= S/He's a law unto herself/himself.

"Creerse el ombligo del mundo" sería "To think the sun shines out of one's arse", ¿no?

Perhaps "To think oneself the centre of the universe" ?

(The Greeks believed Delphi was the 'omphalos' = navel of the Earth, meaning the centre)

ohh ok