Discount brokerages require a minimum age of 18. However, you can create a sub-account under your dads name (as long as he signs some sort of consent form) and these sub-accounts don't have a minimum age requirement.
Vitamin D deficiency rickets can be caused by a lack of vitamin D in the diet, a lack of exposure to the sun, or malabsorption syndromes in which there is an inability of the intestines to adequately absorb nutrients from foods.
Vitamin D Deficiency. Vitamin D deficiency occurs when there is insufficient sunlight exposure and the recommended intake is too low over a period. According to the Office of Dietary Supplements, rickets and osteomalacia are the primary diseases associated with vitamin D deficiency.