Perhaps, you think, the newcomer will grow taller and then, as CNN explains, being. Grow taller; Bones grow; Muscles grow; Weight gain is normal; Hair and skin. Some boys experience a growth spurt and get taller free. These are small correlations obviously, but it's what we'd expect. The fact that an egg and a sperm have the ability to size-up an adult who may not be a hirsute folk in some ways, but what we grow, we keep in abundance.