His biological father had never been in the picture, so his uncle became his role model.

in 在这里表示"处于某种状态或情况中"。 the 是定冠词，特指某个特定的事物或情况。 picture 本义是"图画、照片"，在这里引申为"生活场景、画面"。 in the picture 这个短语在这里比喻"参与某人的生活、出现在某人的生活场景中"。