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.
Some people may not have any symptoms of vitamin D deficiency and still be deficient. The symptoms of vitamin D deficiency are sometimes vague and can include tiredness and general aches and pains. Some people may not have any symptoms at all. If you have a severe vitamin D deficiency you may have pain in your bones and weakness, which may mean you have difficulty getting around.