Did you ever see someone and spend the rest of the day trying to figure out how you know that person?

Janelle Pierzina is on the opposite side of that question nearly every week. As a reality-TV-star-turned-Realtor, Pierzina gets that quizzical look wherever she goes, whether it’s on a grocery-store run with her three kids or hosting an open house for Edina Realty.

“They go through this whole list of questions like, ‘Did you work at 3M?’ ” she said. “So after like 10 questions, I usually just tell them I was on TV.”

And not just any show. She was a star on “Big Brother,” the CBS prime-time hit that locked 10 strangers together in a house while cameras recorded their every move.

Now she’s selling houses in the south Twin Cities metro area, using some of the skills that kept her from being kicked off “Big Brother.” (She shares the record for most days in the house: 177 over three seasons.)

“You have to be very, very good socially, and I feel like real estate’s the same,” Pierzina said. “People have to like you; that’s the biggest thing.”

Former reality TV star turned Realtor Janelle Pierzina showed clients a house in Savage.

Luckily, Pierzina is incredibly likable. She’s honest about her experiences in the entertainment industry. (Note: If you have to choose a celebrity to meet, Jennifer Aniston is one of the nicest.) And she’s willing to talk about whatever crosses her mind, whether that’s Drake’s newest album or her working-class childhood in Grand Rapids, Minn.

“I didn’t have a lot,” Pierzina said. “In junior high, I had like two or three pairs of pants and four shirts, and shoes from Wal-Mart, but it was fine.”

After her parents divorced, her mom, Ann Pierzina-Killian, became a nurse, working odd hours and struggling to raise her kids as a single mother. Pierzina helped out with the younger siblings.

“She would get up all by herself and make herself breakfast,” Pierzina-Killian said. “I worked the afternoon shift, so I would basically set her alarm and tell her she had to get to school on time.”

Her mother believes Pierzina’s upbringing built a spirit of determination that was a huge help on “Big Brother” and beyond. As a teen, she tried out for cheerleading and made the team, even though she was younger than everyone else.

“She’s never been spoiled, never been given life on a silver platter,” Pierzina-Killian said. “If she wanted something, she put her mind to it and did it.”

One thing Pierzina wanted was to be a top TV anchor. “She liked to be top dog,” her mom said. “She always just liked to be in the limelight.”

‘Intense and competitive’

Pierzina, 37, studied communications at the University of Minnesota Duluth, where she met her future husband, Jess. (He owns a hotel in Apple Valley, which is what originally brought Pierzina back to the Twin Cities area; they live in ­Lakeville.)

She eventually decided that wasn’t the path for her and moved to Miami, where she was a model and cocktail waitress before trying out for “Big Brother” in 2005.

Her mom, nervous about how Pierzina would be portrayed, told her she shouldn’t go on the show.

“There was a lot of stigma because reality TV was still kind of new and you didn’t know what [producers] were going to do,” Pierzina said. “You’re signing your life away, basically, and they could make you into anything.”

But Pierzina was happy with her portrayal. She finished third, then was picked by viewers to compete in an all-star edition the following year. She took third once again.

“I played the whole ‘dumb blonde’ thing and it worked because everyone thought I was dumb,” said Pierzina, who returned to the show in 2012 but was evicted halfway through. “My whole character was this tough girl who was kind of at the bottom and I just fought my way to the top.”

That competitive nature has served her well as a Realtor — and sometimes takes people by surprise.

“The first time I met her, she was very sweet and pleasant,” said her boss at Edina Realty, Craig Kanis. “I didn’t know how intense and competitive she was.” Pierzina consistently ranks in the top 10 out of about 80 agents, he said.

Her status as a fan favorite doesn’t hurt, either.

“I get called to people’s houses all the time for weird appointments where I don’t know them but they know me,” she said. “They’re usually pretty excited to work with me. They choose me out of the other Realtors because they feel like they understand me and know me as a person.”

Others, though, know her only as Janelle the Realtor. Sarah Bell and Jake Revak, an engaged couple shopping for their first house, don’t particularly care that she used to be on TV.

“We found out about that later, but that doesn’t really affect anything,” Bell said.

Despite being voted “America’s Choice” during her time on the show and receiving such gifts in the mail as a Swarovski crown and jewelry from Tiffany’s, Pierzina doesn’t see “Big Brother” necessarily as the formative experience of her life.

“It’s just something I did in my life, like a job or whatever,” Pierzina said. “It’s a weird job, but I did it.”

Kelsy Ketchum is a University of Minnesota student on assignment for the Star Tribune.