Pecking Behavior

[Rachealx4]

My BO chicks are about 3-4 weeks old. Is it normal for a chick to continuously peck at your nails even if they aren't long? What about pecking/ biting at your arm where there are no sores, freckles, bandaids, etc and drawing blood?
I have a couple that do this. It's not a huge deal, I'm just wondering if I need to do something different.
Pictures of some of my crew just to show them off

 

[azygous]

Pecking can be obsessive compulsive. It can become a habit. You can break this habit by giving the chick a sharp, but not too hard, poke on the back with your finger each time it engages in the behavior. Chicks respond quickly to this discipline because it's how a broody hen keeps her chicks in line.

 

[Crazy for Chickens!]

They may be deficient in something. Do you have grit for them?
Also, try picking some some little green grass, if you have any, grinding I to small bits, and lettynbg them eat it. It really good for them, plus they love it! Small bugs they love, too.
But, I've had some do hat before. Now, I don't think I would Lt them draw blood, but they are probably just curious.