It's a valid question. Many of us do not have binocular vision. It is one of those things that if you are born with it, you love it. If you never had it to begin with, you have no idea what it is like.

Some possible reasons a person may not have binocular vision is an ocular muscle imbalance or amblyopia, also referred to as a lazy eye. If you have binocular vision your two eyes are able to fuse two images together and provide a three dimensional view.

If only one eye is used depth perception is compromised. Being as every human being is capable of incredible feats, people born with an amblyopic eye are able to use clues from the environment, such as shadows and image sizes to interperate where the image is spacially located.

Using contact lenses for monovision will hinder ones binocular vision, but when fit properly and proper adjustment time is allowed most monovision wearers adapt very well.