I agree diet and proper nutrition and optimal digestion can do wonders, improving my diet over the years, cleansing, taking good quality supplements like probiotics and spirulina/chlorella/turmeric helped improve my health and digestion to a great degree.
But reading about broda barnes research and both dr starr's and brownstein's agreement that babies born to hypothyroid mothers will typically not develop normal functioning thyroids really hit home for me. As i was born with a weak immune system(low thyroid), digestive problems and wouldn't have made it to my first birthday if not for advances in modern medicine. In spite of cleansing, eating healthy, and taking supplements throughout my 20s, it still feels like i was born with only half a thyroid, or one that can't go any higher than 2nd gear.