Indeed MawBroon - there are cases of rickets in children now because their parents have been so careful never to expose them to sunlight, using high factor sunscreens, hats etc.
I think that UV swimwear for young children is excellent, especially in hot, sunny climates, as it does protect but doesn't cover completely, therefore allowing some exposure to the sun.
We may all have examples to prove the theory one way or another. DH had an aunt who used to bake in the sun and her skin was quite leathery; however, she was still hiking at age 90 and went on to live well into her 90s.