Grammar
N3AI-drafted〜くせに
even though; despite (with blame)
Formation
名詞修飾形（V普通形／い形容詞／な形容詞+な／N+の）+ くせに
Usage
Like 〜のに it marks a contradiction, but it always carries the speaker's criticism, contempt or annoyance toward the person concerned. It is casual, spoken language and should not be used about a superior or in polite situations. The subject of both clauses must be the same person, and it is usually not used about the speaker.
Examples
知っているくせに、教えてくれない。
しっているくせに、おしえてくれない。
He knows, yet he won't tell me.
子供のくせに、生意気なことを言うな。
こどものくせに、なまいきなことをいうな。
Don't talk so cheekily when you're just a kid.
下手なくせに、人のやり方に文句ばかり言っている。
へたなくせに、ひとのやりかたにもんくばかりいっている。
He's bad at it himself, yet he does nothing but complain about how others do it.