It's one of the worst-kept secrets of family life that all parents have a preferred son or daughter, and the rules for acknowledging it are the same everywhere: The favored kids recognize their status and keep quiet about it - the better to preserve the good thing they've got going and to keep their siblings off their back.

The golden child may be the oldest one, unless it's the youngest. It may be the toughest one, unless it's the most sensitive. It's not even necessary that Mom and Dad have the same favorite - and typically they don't.

When we're awake, cortisol can fragment memories - one reason eyewitness crime scene accounts are so unreliable. But at night that very fragmentation allows creative recombinations of ideas.

Identical twins are ideal lab specimens for studying the difference between learned and inherited traits since they come from the womb preloaded with matching genetic operating systems. Any meaningful differences in their behaviors or personalities are thus likely to have been acquired, not innate.

The best you can sometimes do is learn to take a breath, count to ten and simply accept that try as you might, no, your husband will never, ever learn not to drop a wet towel on the bed. That acceptance too counts as resolving a fight.

There's a sort of sibling moratorium when you're establishing yourself as an adult. So much of your energy has to be focused on other things like work and kids. But when people become more settled, siblings tend to regroup because now you're building a new extended family.

As MBA professors endlessly tell their students, companies do best when they stick to what they do well. There's a reason Apple doesn't make blenders. There's a reason Haagen-Dazs doesn't sell meat. And there's a reason drug companies should focus on saving and improving lives - not jeopardizing them.