When it comes to personal social media, you see a lot of people with really non-existent bios. Facebook is (usually) not so bad, because most of what you say is shared only between people you know, but Twitter is a very public medium.
It’s also pretty important to note that if you’re running a Facebook page about yourself, you NEED to have a decent bio. “Hey, I’m a person. Lol.” isn’t a good bio. Explaining what you do is a good start. However, you need to remember that if you even imply some relationship to any organisation that you are involved with, you can get in trouble if you say the wrong thing. Also, if you share a link that offends people, you are guaranteed to have people assuming you and/or your workplace endorse that link.
This is why your bio is so important. Sure, put what you do, but ALWAYS include TWO additions – the second is one that most people leave out, but could be just as important. The first part should be something like “All content belongs to me” or “Opinions are all mine”. The second part should be something like “Links (and RTs) do not imply endorsement”. That’s important. If you retweet someone, and they end up doing something stupid, you don’t want people saying you’re endorsing their stupidity. It’s all about protecting yourself.
You get car insurance in case something goes wrong. This is social media insurance.