The single best predictor of whether a person will vote when first eligible and will later become a lifelong voter comes down to one discreet action by that person’s parent: Whether that parent voted in the presidential election just before their child could vote.

That’s one of the takeaways from a long-term study of families nationwide that has shed some of the only light political scientists have on parent-child political influence.

Laura Stoker, a political scientist at the University of California, Berkeley who co-directs the study, told me that a parent’s vote at the time of adolescence is the only consistent variable in any analysis of predicting whether a young adult will vote.

The study, which Stoker joined mid-way through, began in 1965, when another political scientist, Kent Jennings, interviewed more than 1,660 high school seniors and their parents about their political leanings, participation and affiliation.

Researchers then reinterviewed the group in 1973, when the younger subjects were 26; in 1982, when they were 35; and in 1997, when they were 50. The last year, researchers also interviewed the third generation.

I’ll post tomorrow on what those interviews showed in terms of parental political influence with regard to party affiliation and ideology.

For today, I’ll focus on engagement.

Stoker said if parents were civically engaged, if they were active voters through the child’s life, if they discussed politics frequently, with the child or even with other adults in conversations a child might overhear, kids were more likely to be politically engaged themselves as adults.

No surprise there.

What was more surprising was that even if none of the above occurred, which Stoker said was most often the case (presumably outside of Washington), it didn’t mean a child would disengage.

He was less likely to be politically active, yes, but not necessarily less likely to vote.

The key to transmitting to the next generation the sense that voting is a duty or privilege or responsibility, notions that many Americans embrace even if they don’t talk much about their political views, is casting a vote in an election when a child is almost ready to do so himself.

Stoker said separate research has consistently shown that once that first vote is cast, a person is far more likely to keep voting.

The parental transmission study doesn’t get at why this is, or why it doesn’t much matter if a parent drags a child to the polls from birth on up.

Stoker has a few theories.

She said adolescents may be developing a “script” for how to actually go through the process of voting. Just as they might pay more attention to how a parent drives a car in the months before they take a driver’s test, they may be more attuned to the logistics and motivations of voting during adolescence.

More, Stoker thinks, presidential elections are a time of when education and home life are likely providing similar lessons about civics, democracies and electoral politics.

That creates a synergy in an adolescents's life that, she said, reinforces a consistent message about the importance of voting.

Another interesting nuance: A parent’s act doesn’t have to be a conscious “teachable moment.” It just has to be a vote.

Have you talked with your kids about the election and about voting? What do you hope their takeaway is from the election?