August Weismann cut off the tails of mice for 21 successive generations and still they produced generation after generation of only tailed young ones. So he concluded that acquired characters are not inherited.

Cretinism is a disease caused by hypothyroidism(less thyroxine formation).The symptoms of the disease are retardation  of mental, physical and sexual developments. Potbellt, protruding tongue, dry skin etc are also indicative of this disease.