Face Book Crush

There's an acquantance I met through mutual friends who just so happens to have a brother slightly younger than she is. I discovered this through her Face Book. The few times that I actually go on. The first time I saw her brothers picture I was interested. He was attractive (although not fiiiine), he was tall, seemed laid back and friendly in all of his pictures. Pictures, of course don't say a lot about a person but it can tell you a few things especially their profile. So many times I have thought of messaging him through face book and simply saying Hi or something similar. Now, I must say that I am big on privacy especially when it comes to my romantic life and I have never been a fan of online dating. However, I'm fearful that it looks "weird" since I don't really know his personality I'm fearful that he may be the blabber mouth type and tell his sister or simply ask her who I am because I messaged him and that to me would very embarrassing.
Growing up with a traditional family doesn't help either. They tought me that love finds you etc.
Am I being too reserved and close minded here guys?
What are your thoughts on this?