Sure, they're all Democrats and most lean well toward the left. But with one congressman defeated, another retiring and new political maps drawn by California's trailblazing citizens redistricting panel, the Bay Area's House delegation for the upcoming 113th Congress is noticeably different.

It's younger. It no longer contains Congress' only professed atheist. And its priorities are more varied.

Here are some things to know about the Bay Area Dozen:

Not spring chickens, but ...

The turnover is unusual. The last time the Bay Area saw two freshmen sworn in at the same time -- as will happen with Eric Swalwell and Jared Huffman -- was 20 years ago, when North Bay Rep. Lynn Woolsey and Peninsula Rep. Anna Eshoo took office the same day.

At the beginning of 2012, the average age for Bay Area House members was 68, more than a decade older than the average age in a Congress that was among the oldest in U.S. history. But when the 113th Congress begins at noon Jan. 3, the Bay Area delegation's average age drops to 62.

Voters replaced 81-year-old Pete Stark with the 32-year-old Swalwell, D-Dublin. The retiring Woolsey, 74, was replaced by Huffman, 48. And redistricting gave Napa-based Mike Thompson (61) a part of Contra Costa County that used to belong to John Garamendi (66). Swalwell will be the youngest of the new Bay Area delegation. At 72, House Minority Leader Nancy Pelosi, D-San Francisco, will be the oldest.

"Usually freshman members are more responsive to their constituencies," eager to stay in voters' good graces at least until they've started cementing their tenure with a second term, said James Cottrill, a Santa Clara University political-science professor.

They also can be likelier to seek juicy pork-barrel spending for their districts, he said, but a lack of seniority, a Democratic minority and a tight budget could blunt these new members' efficacy.

Ya gotta have faith

Stark's defeat means Congress is now without any avowed atheists, though there's a new Democratic Arizona congresswoman who lists her religion as "none." But Kyrsten Sinema reportedly considers herself "secular," not an atheist. Stark's replacement, Swalwell, describes his faith only as Christian, while Huffman is even less specific, calling himself "nondenominational." Of the rest of the Bay Area delegation, Pelosi, Thompson, George Miller, Jerry McNerney, Jackie Speier and Anna Eshoo are Roman Catholic; Barbara Lee is Baptist; Zoe Lofgren is Lutheran; Sam Farr is Episcopalian; Mike Honda describes himself as Protestant, without any further specificity.

But faith isn't always a good predictor of policy. For example, while former GOP vice presidential nominee Paul Ryan's Catholicism informed some of his social-issue stances, the Bay Area's House members who are Catholic differ from their church's teachings by supporting abortion rights and marriage equality.

"Once upon a time Catholics toed the line on those issues ... but like so many other groups, this is becoming less so," said Larry Gerston, a San Jose State political-science professor.

Said Cottrill: "The Catholics here in the Bay Area delegation are more the social justice and social welfare type of Catholics than those who would focus on issues like abortion."

Shifting priorities, widening portfolio

No Bay Area member has sat on the House Transportation and Infrastructure Committee -- with dominion over highways and transit projects vital to urban centers like the Bay Area, especially as an improving economy brings resurgent congestion -- since the East Bay's Ellen Tauscher, who resigned in 2009 to take a State Department post. Swalwell -- who interned for Tauscher in 2001 and now has her advising his transition team -- has told House of Representatives leaders he's interested in a seat on the panel, which also has input into major projects such as California's nascent high-speed rail line.

Gerston noted that Swalwell ignored his party's wishes in unseating Stark yet now wants to be assigned to a hot committee that doles out a lot of public money. "Whether he gets that committee will be an interesting insight into what extent the old guard has accepted this new buck in light of the way he won his office," he said.

Elsewhere, Huffman, D-San Rafael, has talked of applying his experience as an environmental attorney, so perhaps he's interested in the Natural Resources Committee, which deals with energy production, water, parks, fisheries and wildlife. If appointed, he would be the Bay Area's only voice there, now that Garamendi's district has moved entirely out of the region.

Stark was the ranking Democrat on the Ways and Means Health Subcommittee -- which oversees the purse strings for Medicare, Medicaid and other health care and health research programs. But Thompson is the next-most-senior Democrat there, though less experienced than Stark.

Woolsey served on the Education and the Workforce Committee, where Miller is the ranking member. She also served on Science, Space and Technology, which oversees areas from energy research to NASA, but Lofgren, D-San Jose, and McNerney, D-Stockton, also serve on that committee.

Josh Richman covers politics. Contact him at 510-208-6428. Follow him at Twitter.com/josh_richman. Read the Political Blotter at IBAbuzz.com/politics.

Their former lives
Before they were elected to the House of Representatives, members of the Bay Area's delegation had a variety of professional backgrounds:
Anna Eshoo, D-Palo Alto: Administrative assistant at Aluminum Company of America and Arcata National; San Mateo County Democratic Party chairwoman; legislative staff member; county supervisor
Sam Farr, D-Santa Cruz: Peace Corps volunteer, legislative staff member, Monterey County supervisor, Assembly member
Mike Honda, D-Campbell: Peace Corps volunteer, science teacher, school principal, school board member, Santa Clara County supervisor, Assembly member
Jared Huffman, D-San Rafael: Consumer and environmental attorney, Assembly member
Barbara Lee, D-Oakland: Social worker, congressional staff member, Assembly member, state senator
Zoe Lofgren, D-San Jose: Congressional staff member, immigration attorney, community college board member, Santa Clara County supervisor
Jerry McNerney, D-Stockton: Engineering contractor, wind energy engineer and consultant
George Miller, D-Martinez: Attorney, legislative staff member
Nancy Pelosi, D-San Francisco: Democratic National Committee member, California Democratic Party chairwoman, Democratic Senatorial Campaign Committee finance chairwoman
Jackie Speier, D-San Mateo: Attorney, congressional staff member
Eric Swalwell, D-Dublin: Deputy district attorney
Mike Thompson, D-Napa: Army veteran, vineyard owner and maintenance supervisor, university instructor, legislative staff member, state senator