Baron Bear Beard Blackfyre

Here is a riddle, To all things and men I appertain,

and yet by some am shunned and distained.
Fondle me and ogle me til you’re insane,
but no blow can harm me, cause me pain.
Young ones delight in me, elders take fright.
Fair maids rejoice and spin.
Cry and I weep, yawn and I sleep.
Smile, and I too shall grin.
What am I?”