Does anyone know about breeding rats?

i have always been curious about rat babies. i prefer to keep boys myself as dont want millions of rats in the house at any one time but ive seen loads of pictures of really young rats (pinkies i call them, lol) being held up to a day after they have been born. surely the mother wouldnt let you touch them, or she would smell you and kill them? i thought you are supposed to wait till they had hair. my mum bred them a few years ago and she was strict with us about never touching the babies until they were at least two weeks old .. does anyone know about any of this??