younger marks

日本語にもなっているような中学生レベルの英単語でもいまだに意味が分からないのが英語です。次に引用するNet Forceに出てきた "marks" の意味が分かりません。
Rachel listened patiently to Alain's tale of grievance and revenge, nodding in all the right places and looking interested. Normally she wouldn't have wasted her time--these younger marks were almost without exception pitifully self-centered, and would talk the sun out of the sky and your patience into rags if you let them.
早速 "marks" を辞書で調べます。
・Oxford English Dictinary: A characteristic property or feature: 'it is the mark of a civilized society to treat its elderly members well’
・Merriam-Webster's Online Dictionary: a distinguishing trait or quality :  characteristic: the marks of an educated -
・Wiktionary: A characteristic feature. [from 16th c.]: A good sense of manners is the mark of a true gentleman.
答えを知ってしまうと、なーんだそうだったのかと自分の推測力のなささにがっかりです。この "younger marks" の後にある "talk the sun out of the sky" の意味もよく分かりませんが、宿題にしておきます。