There are many reasons why some can grow facial hair and some just can’t, and it is mostly genetics related. You are just not “man” enough. Seriously speaking, you testosterone level is relatively low. This wonderful enhancement to a male body depends on the interaction between testosterone and existing hair. This doesn’t mean that higher testosterone level produce thicker, lusher beard.
Most men have the same amount of testosterone, and what the genetics kicks in is how the body responds to its testosterone level to results in the growth of facial hair. If you are more sensitive to your testosterone, you will grow a bushier facial hair. On the downside of having more hair on your face, balding is more prominent for the ones that can grow a full beard. So there is that trade off you can appreciate if you are feeling down on lacking a beard. And if you are going to be bald, at least you can grow the symbol that epitomizes masculinity. So, the capacity of whether you can grow a beard depends on your parents, and if the genetics lottery has been kind, you will be able to grow a beard.