I believe that the three systems are; Respirtory, Digestie, and Circulatory.
most likely a full beard will grow in in a few more years. not every body gets a beard at such a young age as 20. be patient it will come. be happy you are still looking for hair to grow in as opposed to losing hair when older.
Skeletal, muscular, nervous
your skin, your hair, and your nails.
Digestive, urinary and reproduction
The digestive system, respiratory system, circulatory system
There are three main body systems for support and locomotion: the skeletal system, the muscular system and the nervous system. There are others that are secondary support systems including the cardiovascular.
there are three Major systems that control basic body movement, the muscular system and skeletal system; both controlled by the nervous system.
There are three systems that are part of the cardiorespiratory system: circulatory, blood and lymphatic systems.
Because it's the body type
Yes, some people are born with a birth defect that can cause a man or a women to both have female and male hormones. such as a man growing breasts, or a women with a beard.
facial hair grows when you hit pubrty or (your body changes