Not to ruin any Appeal to Authority, but no they have not "always disagreed"
"Biology says chromosomes, DNA, and skeletal systems, as well as endocrines cannot be altered."
No it doesn't.
General biological changes that occur with aging say otherwise, as do genetic mutations, which also accumulate as organisms age. Cancer is one possible result of said genetic mutations, as well as genetic abnormalities which increase among the offspring of older parents.