What does すねるたちで mean?

Question

i know that たち　could be the 2nd stem of たつ　or could be the plural indicator, and i sound a definition of すねる　on jisho.org which said

Ichidan verb, intransitive verb 1. to be peevish; to sulk; to pout​Usually written using kana alone

however in the context of the sentence, i can't make sense of it let alone work out what it means with たち attached.

for context, the sentence is:

すぐにすねるたちで、すねた横顔はジェームズ・ディーンに似ていた。

Answer 1

The 「たち」（質） is a noun and means "one's nature" "disposition" (≂ [性質]{せいしつ}/[気質]{きしつ}).

「すぐにすねるたちで、～～」 "(He) easily gets peevish/sulky..."

A few examples:

父は怒りっぽいたちだ。 My father loses his temper easily.
彼女は頼まれると断れないたちです。 She (is the type of person who) can't refuse a request.