Final answer:
A lack of vitamin D can result in the development of rickets in children and osteomalacia in adults, which lead to skeletal deformities, weakened bones, and contribute to conditions like osteoporosis.
Step-by-step explanation:
Rickets is a childhood disorder characterized by improper bone development due to a deficiency in vitamin D. The malabsorption of calcium and phosphate, which are essential for bone mineralization, leads to skeletal deformities and weakened bones. Lack of vitamin D can result in the development of rickets in children and osteomalacia in adults, which contribute to conditions like osteoporosis.