If you use simple 4 digit passwords then you are at risk.
4 digit passwords, all in lower case can take .046 seconds to hack.
Read more about how quick a hacker can hack your passwords at One Mans Blog.
After you have read that article you want to consider downloading RoboForms FREE Password Manager.
Read my RoboForm article to find out more about how RoboForm works.
Then may be change your passwords to 8 digits using all characters like this: j!B$3h7e
It's common for people to use simple names, DOB, friends names, pets name, places they live etc. The information you store and access online can be personal, best to keep it that way.