Laundry times three

When I bought a new washer and dryer two years ago one question the salesman asked me was how many loads of laundry I do in a week to which I replied three, sometimes four.  He was astonished that the total could be so low (he's the father of three boys) but I reminded him that I live alone, except for my cat and she doesn't require much in the way of laundry.  Today, as I was washing a weeks worth of laundry for the two grandchildren visiting with me, I was reminded of how it used to be when I had two kids living at home.  I don't understand how three people can generate five times the laundry of one person. It doesn't seem mathematically sound, but, never-the-less, it happened.  And we won't even mention the astronomical increase in socks without partners.  As Irma Bombeck once said "It's a sad but true fact that socks do not mate for life."