My hearing is slightly better in my left ear. is this a normal scientific fact? if not, what can i do to check and make sure nothing is wrong with it?

Don't bother: Different people's hearing is often better in one ear or the other. If you have adequate hearing in both and are getting around okay, you're probably not doing any good by looking for an explanation. Avoid very loud noises, have your physician help if you get too much earwax, get checked if your develop symptoms, and generally pursue a healthy lifestyle.