There’s a picture pinned to the bulletin board in my kitchen, half hidden by silly greeting cards and bumper stickers that I fancy, which is our iconic family back-to-school photo. In it, my oldest two children stand on the front step of our old house, a basket of late-summer impatiens drooping behind them, on the occasion of the eldest’s first day of preschool, just shy of his fourth birthday. These were the days when they dressed in what I picked out for them, so they are wearing patterned, elastic-waist shorts – his in plaid and hers are floral – with their polo shirts neatly tucked in. …