hm.. does this mean "did he have children?" or "was he a child?" both seem irrelevant to the context of the book I'm learning from :/
Judging from the all-kana sentence, I'm guessing that this is a beginner question, and as naruto answered, it means "Was Mr. Yamashita a child?" without any other context.
That said, and just for the fun of scaring beginners, this sentence can also mean "Does Mr. Yamashita have children?", specifically "You, Mr. Yamashita, have children, right?"
This is variation on the 僕はうなぎです scenario, for those familiar with it.