The reason your leg bones are curved is a result of abnormal bone development also known as bone dysplasia.
Curved leg bones are also known as knock knees or bowlegs.
Other things that can lead to curved leg bones are normal growth disorders and other underlying medication conditions and sometimes it's a normal development.
In children that have curved leg bones or bowed legs, it is common during the first year of the child's life and is normal as a part of normal development.
Although if the leg bones bowing or being curved persists after that then it can be a result of the rickets, Blount's disease or other growth abnormalities.
Bowing of the legs in adults or curved leg bones can also be a result of osteoarthritis or other issues with the joints.
Blount's disease which is also known as tibia vara, is a growth disorder which affects the growth plates of your shin bone also known as the tibia.
Blount's disease causes the leg to turn inward and bend to resemble the curve in the letter C.
Lack of vitamin D or calcium can also contribute to bowed or curved legs and it's more common in countries in which children don't get enough foods that are fortified with vitamin D.
Having curved legs or bowed legs as an adult can be the result of osteoarthritis or wear-and-tear arthritis of the knees.
These conditions can wear away the cartilage and surrounding bone of the knee joint.
If the wear is more on the inner side of your knee joint, a bow-legged deformity may develop.