Kellogg was a staunch advocate of abstinence, believing that sexual activity was detrimental to health and vitality. He promoted his views on sexuality in his writings and lectures, often advocating for extreme measures to suppress sexual urges.

Kellogg controversially suggested measures like sewing boys' foreskins and cauterizing girls' clitorises to prevent masturbation. These ideas are now universally condemned as unethical and harmful.

Kellogg was a proponent of eugenics, a now-discredited movement that sought to improve the genetic quality of the human population through selective breeding and other measures. He believed that eugenics could help to prevent disease and social problems.

Kellogg's views on sexuality and eugenics reflected the prevailing prejudices of his time and contributed to the stigmatization and oppression of marginalized groups. His legacy remains controversial due to these harmful beliefs.