Mr. Nadelmann, a boomer himself at 52, says the biggest difference since the last legalization push, in the late 1970s, is the drug savvy of parents now versus then. “In the ’70s, that older generation of parents didn’t know the difference between marijuana and heroin,” Mr. Nadelmann said. “This generation of boomer parents has a high familiarity with marijuana. An awful lot tried it, liked it; the vast number never went on to cocaine or heroin or even had a problem with marijuana.”

That would be me. The 20-something me used marijuana in moderation, did not fall victim to reefer madness, did not go on to harder drugs, believed it to be a drug superior to alcohol in many respects, enjoyed it like the mayor, and inhaled like the president.

The 20-something me preferred alcohol when socializing in large groups but pot for coupling.

The 20-something me smoked a joint, then went to the Central Square Cinema in Cambridge, Mass., and howled at the 1936 anti-drug documentary “Reefer Madness,” which showed how pot-smoking could lead to hard drugs, murder, suicide, rape and the inevitable descent into insanity. (Afterward, the 20-something me had major munchies and hurried to Elsie’s restaurant for the enormous roast beef sandwich special.)

The 20-something me believes marijuana could be legalized, regulated and taxed like alcohol, providing much needed revenue.

But the 50-something me, the parent of three boys and a girl, ages 14 to 21, is not so sure. The 50-something me  who hasn’t smoked in more than 20 years  knows stories in our little suburb about classmates of my kids smoking pot in middle school, using heroin in college, going into rehab, relapsing, trying again. The 50-something me has seen the eyes of those boomer parents  good people  seen the weariness and fear, and thought, “There but for the grace of God. ...”

Recently I read David Sheff’s best seller, “Beautiful Boy,” about his son Nic’s addiction to methamphetamines, the boy’s myriad rounds of rehab and repeated heartbreaking relapses. And while the problem drug in our house is legal (our boys went through numerous rounds of painful, nerve-racking alcohol-related groundings during high school), I was surprised by how much Mr. Sheff’s book moved and frightened me as a parent.