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.

Some of the most rewarding times my brothers and I have are when all of us get together, and we can see what we've been building genetically and culturally.

Credit or debit cards, for starters, are nothing short of shoppers' Novocain. Even in the age of digital purchases and virtual money, we still attach a special value to dirty paper with pictures of presidents on it. Handing some of that to a cashier simply hurts more than handing over a little sliver of plastic.

As the National Football League and other pro sports increasingly reckon with the early dementia, mental health issues, suicides and even criminal behavior of former players, the risk of what's known as chronic traumatic encephalopathy (CTE), is becoming clear.

Operating-room errors hold a special terror for patients, if only because they seem like the most avoidable kind of complications. The occasional horror stories of patients who have the wrong leg removed or the wrong knee replaced generate the most headlines, as do tales of patients whose identities are mixed up entirely.

Vaccines save lives; fear endangers them. It's a simple message parents need to keep hearing.

Sisters have ways of socializing brothers into the mysteries of girls. Brothers have ways of socializing sisters into the puzzle that is boys.