be at the bottom of

be/lie at the bottom of something

to be the real reason for something unpleasant I don't know for certain why she dislikes you, but I suspect jealousy is at the bottom of it.

Name	Pronounced	Usage
Evaristo	e-vah-REE-sto (Italian)	Spanish, Italian, Portuguese
Aggy	['ædʒi]
Rubinho	-	Portuguese
Trevor	['trevə]
Jeremias	ye-re-MEE-ahs (German), YE-re-mee-ahs (Finnish)	German, Portuguese, Finnish
Egan	['i:gən]