eek - there's a mole.

that was the cry that greeted me this morning.
and when doris yells, the moon's gravity is disturbed and the threat of earth's extinction looms ever closer.
so i ran upstairs with two three foot cushions fastened to my ears with a snake belt and asked calmly what she was on about.

she pointed to her arm - i've got a mole.

obviously, this was disturbing for her.
she has lots of moles, all over her body (i counted them once during our more romantic days, starting on her foot, and working my way up) - if i tried to do that now, i'd need a stepladder and an ordnance survey map).

anyway, it made wonder about moles.
why do we get them?
i've got lots but only on one arm.
why is that?

is it like mushrooms that grow in one spot in a field, and nowhere else?

any ideas?