Dog trained to protect his sister

Shepherds are the most loyal and best friends, I had mine for a few years. Rest in peace my friend

Aw, what a good pupper. I had a dog that was very protective of me as well. I'm hoping my shepherd will be like this with my son...we're in the process of training her but she's so damn lovable I'm not sure she's capable

My mum had a shepherd about 30 years ago that she still talks about regularly to this day. Apparently Ike was the most protective and loveable doggo she's ever seen.

Puppy!

What kind of life do you lead where you need to have a multi-thousand-dollar trained dog to,protect your child like this?