(Jon Davidson, Office of President Clinton)

Theories abound about why young voters in general, and young women in particular, do not support Hillary Clinton in the Democratic primaries.  Such speculation will surely intensify after the New Hampshire primary, where Clinton won only 16 percent among 18- to 29-year-olds en route to losing to Bernie Sanders.

Here is one important explanation for why many young Democrats do not support Hillary Clinton: They have not yet parented a daughter.

The economist Atif Mian raised this possibility last week.  He connected Hillary Clinton’s poor performance with young voters to my previous post showing that parents of daughters are more likely to prefer Clinton over Sanders than are parents of only sons:

The data certainly support his statement.  And it’s not just because 18- to 29-year-olds have far fewer daughters than older people. It’s because the “daughter effect” is particularly pronounced for young people:


Graph by Michael Tesler: Note: Results control for total number of children.

The graph is based on the eight biweekly YouGov/Economist surveys conducted since Joe Biden announced that he would not run for president. It shows that young parents of daughters are between 21 and 48 percentage points more likely to support Hillary Clinton than young parents of only sons (after accounting for their total number of children).  By contrast, the daughter effect on Clinton support for parents ages 30 and older is between 5 and 13 points.

The daughter effect on younger voters is so strong, in fact, that younger parents of daughters are just as likely to support Hillary Clinton as their older counterparts.

We must be careful extrapolating from these results, of course.  But some back-of-the-envelope calculations suggest that Clinton could be as much as 8 to 18 points more popular with young adults as a group if they had daughters at the same rates as older Americans.

Why would having a daughter matter more for younger Americans than it does for older voters? Here are two complimentary explanations.

First, a female president may mean more to parents of younger children because their kids have not yet forged their own paths in life.  President Obama echoed that explanation a few weeks ago.  The president responded to a question about the significance of having a woman succeed him in the Oval Office by saying, “… I want more women in politics generally, and I want my daughters to feel that there’s nothing that they can’t do.”

Second, a long line of research shows that young adults tend to have less crystallized political attitudes than older people. Young voters, therefore, have fewer and weaker political considerations to draw from when choosing between Clinton and Sanders. This leaves room for other factors, like their child’s sex, to matter more.

Consistent with that second reason, the daughter effect on Clinton support is also concentrated among Americans without a college degree, who like young adults, have less crystallized political beliefs.

Obviously, the daughter effect is hardly the whole story here. Nevertheless, it is a key reason why most young voters prefer Sanders to Clinton.

Michael Tesler is assistant professor of political science at UC Irvine, co-author of Obama’s Race, and author of Post-Racial or Most-Racial? Race and Politics in the Obama Era.