Who's the Mom? The Internet Is Struggling to Decode This Viral Photo

— -- It's a question that has stumped the Internet. Who is the mom in this photo?

When Kaylan Mahones posted the family photo on Twitter last week, she had no idea she'd create such a frenzy.

The photo, captioned "Mom, twin & me," has been re-tweeted over 19,000 times.

"When we go to the store, people always ask [my mom] if this is our big sister. We got that sometimes out in public but I didn't really know it was that deep," Kaylan, who has a 16-year-old twin sister named Kyla, told ABC News.

Her mother, Tina Brown, agreed.

"I didn't realize how much we looked alike or how big of a deal it was for people to think that we look more like sisters, versus mom and daughters although we do get that a lot," she said.

Brown, 35, said many family members look younger than their age. Brown, unfortunately, does not have any secrets for staying young.

"I do try to drink water although I don't drink as much as I should," she said. "While looking nice on the outside is great...I do teach the girls to focus more on education and inner beauty."

So, who is the mom?

"My mom is the one in the black and she's on the left," Mahones said with a laugh.