Having been born into a poor family, he craves wealth.
Literal
Poor family [to-に] was-born [because-ので] he [topic-は] wealth [object-を] is-wanting.
生まれたので uses ので for an objective cause — 'because he was born into.' 欲しがっている uses がる (showing signs of wanting) in ている form, appropriate because we're describing someone else's desire. Japanese restricts 欲しい to the speaker; for others, 欲しがる is required.