Wool is the hair of a sheep, one would think it would be okay to turn cut off hair into sweaters etc.

but you would be wrong to think that because for a sheep it's no hair cut. Sheep in the wool industry have been genetically modified to produce ALOT of wool.

A big problem with that is the sheep have extra folds of skin for more surface area for wool to grow. When being sheered often times the folds of skin get caught in the blade. Workers are often paid by how much 'product' not by hour so a worker does not want to spend time being careful. If a cut does occur sometimes it can be deep and the worker must stitch it up on the spot without antiseptic.

Mulesing is commonly practiced to prevent fecal matter from building up in the wool causing infection from flies laying eggs within the wool. Mulesing involves cutting pieces of skin off of a Lambs/Sheep buttocks.

Tail docking is also common just like in the dairy industry where the tails are cut off or elastic bands are tightly put around the tail till it dies and falls off.

And of course when wool production declines the sheep are sent to slaughter.

The good part... There is vegan alternatives so you don't have to pay for this to happen just for an ugly Christmas sweater. Alternatives are commonly made from cotton and they could fool anybody.