I am 40 years old, and in all of my years, I barely found about cutting maybe about 15 years ago from a movie I watched. Just recently, like 6 years ago, I met someone who became a good friend that she did it. And about four years ago, I found out one of my nieces does it too. More recent, like in the last couple of months, I met someone else who does.

My question is how can I be more sensitive towards them because my natural instinct is want to tell at them or slap some sense into them, but... I know nothing about why, what, how... Anything? Any advice?