How old are babies in heaven?

Question:  How old are babies in heaven?

Who knows!  One verse of Scripture that could shed light on it is 1 John 3:2, “Beloved, we are God’s children now, and what we will be has not yet appeared; but we know that when he appears we shall be like him, because we shall see him as he is.”

We know that we will be like Jesus.  Does this mean that we will be like him in physical appearance, or maturity (age)?  I would say that I think so, but Scripture isn’t at all clear on this.