I have small bumps like rash over my arms, legs and chest for weeks nw..it's not itchy at all..now my 9 months old twin boy has that too..

Rash: Did you change detergent? Are the " bumps" very small-? Do you have a pet? Sounds like fleas if not itchy and all over.

Dry skin?: Try applying a moderately thick moisturizer within 3 mins after bathing and see it this helps. It may take a few days however before you can see the effect. If this failed, then consider checking with your doctor. Since dry skin tends to be a familial trait, i think that's the best guess but a direct observation will give a more definite answer.