“Humans were modified, basically, by infections. ... Other diseases could have altered the same genes.”
Unscientific nonsense. Bacterial infections don’t alter human genes. Environmental forces can eliminate portions of the population carrying certain genes, while leaving other portions of the population with other genes to continue their line, thereby SHIFTING the proportion of EXISTING genes in future populations. That’s it. Alteration of percentages of the population with a particular EXISTING gene.
Perhaps some virus could weasel its way into a gamete, but short of that, nada.
during famine, genes turn on to preserve life. Kids are born with their genes on (LOL). When do they turn off? do you know?