Conjunction/particle expressing criticism, surprise, or dissatisfaction that something is contrary to expectation. Often carries a negative or accusatory tone. Attaches to the plain form of verbs, adjectives, and nouns (with な/の).
He pretends to know, even though he doesn't.
He talks arrogantly even though he knows nothing.
That kid talks like an adult despite being an elementary schooler.
He's bad at it, and yet he's totally confident.
He talks back, even though he's just a kid.
ながら marks a mild, often simultaneous contrast without judgment, whereas くせに carries a critical or accusatory tone.
くせして is a blunter, more colloquial variant of くせに with the same critical nuance, often heard in casual speech.
くせに is a colloquial conjunction meaning 'despite being', attaching to whole clauses, while だてらに attaches directly to a noun of social role and has a more literary, critical tone.
くせに adds a critical or sarcastic tone to the contrast, while ものの is neutral and simply factual.
Kanji spelling is attested but uncommon; learners should prefer the kana form.
Katakana variant; sometimes used for emphasis or in informal writing.
Derived from the noun 癖 (くせ, 'habit') + に, originally meaning 'in the habit of (doing something)'. Over time it grammaticalized into a concessive conjunction with a critical nuance.