Rather than answer your student directly, I recommend leading your class through a series of questions so they can answer the question for themselves.
Do human beings have belly buttons? (Yes.)
Why? (Because they were once attached to their mother in utero.)
Is Jesus human? (Yes. He is true God and true man.)
Did Jesus have a mother? (Yes, the Blessed Virgin Mary.)
Was he born of his Mother in the way humans are born? (Yes. Although there is some discussion on this point, it is not necessary to go into the fine details with your students at this time.)
Conclusion: “If we’ve established all that…” [you say to your students], “then you tell me, does Jesus have a belly button?”
DISCLAIMER: Catholic Answers has turned over the archive to Catholic-Questions.org and no longer owns, manages, or moderates the forums. For additional apologetics resources please visit www.catholic.com.