I have a half sister (we share the same dad) that I've never met before. My mum left my dad when I was a baby and he went off, got married and had a baby. I've always known about her but I have no idea if she knows about me.
I was curious a few months ago and easily found her on Facebook, she's now 25 and living in Australia (I live in the UK). I would like to send her a message but I have no idea if she even knows that I exist or if it would come across really weird? Would you do it or just leave it be?