By normal, I mean there are genuine physiological reasons why it exists and these reasons are often important in keeping the child safe. (sarahockwell-smith.com)
The declining levels of testosterone are a natural occurrence for a number of physiological reasons. (strengthsensei.com)
He said «there is no sound physiological reason» power outputs higher than previously recorded could not occur naturally; he did not express any view on today's top performances. (nytimes.com)