In their hearts, Americans are mostly decent, fair-minded and caring people who nevertheless tend to shrink from what they don’t understand. A poll released this week by the Pew Center for the People and the Press lends evidence to that generalization.

The public, Pew finds, is getting more tolerant, perhaps even accepting, of homosexuality. Sexual orientation remains a controversial topic, but opposition to same-sex marriage has dropped from 65 percent in 1996 to 51 percent in the survey taken earlier this month. Support grew from 27 percent to 39 percent during that same span. Strange as it seems, those with no opinion appear to account for the missing percentage.

The trend lines were not steady. Acceptance figures were rising between 1996 and 2003.

Then they started to stagger at about the time the Massachusetts Supreme Court was considering a case in which it ultimately ruled that prohibiting same-sex couples from marrying violated their constitutional rights. Civil unions weren’t enough.

The decision provoked heavy-duty fear-mongering. The wholesale demise of family values in America was predicted.

Those fears haven’t been realized. In various places and through various processes, gay and lesbian couples have been marrying, yet Earth remains on its axis.

In the absence of catastrophe, the upward trend in public approval has resumed.

Let’s be clear. Pew’s figures don’t reflect wide public enthusiasm for gay participation in marriage, adoption or military service, but the poll shows that hostility is waning, both in numbers and in intensity. Consider:

“Sixty percent of poll respondents feel gays and lesbians should be able to serve openly in the military. That’s up from 52 percent in 1994.

“Forty-six percent think gays and lesbians should be able to adopt children. It was 38 percent in 1999.

It’s the trends that make the poll encouraging, not the raw numbers, and it would be unreasonable to think gay and lesbian victims of discrimination shouldn’t be impatient.

Still, reflecting on the patterns of sociological progress through history, Pew’s findings are hopeful.

Familiarity doesn’t always breed contempt. Sometimes it engenders understanding and growth.