Superfit genes run in the family! Meet Selter’s toned mom and grandmother

Good luck keeping up with the Selters. While “belfie” queen Jen is known for her rock-hard abs and bodacious behind, it turns out she got it from her mama — and her grandma. Mom Jill Weinstein, 50, grandma Lois Jacobs, 72, and 24year-old Selter all live in Manhattan and work out together on Wednesdays . And while Selter jokes that both older women have “flat butts,” all three have hot bods thanks to their daily training sessions and low-carb diets.

“Jen motivates me every day,” said Weinstein.

“My mom does crunches every single night since I started my Instagram,” said Selter. “She’s trying to get better abs than [mine].”

“I think I might already have them,” Weinstein quipped.

“Genetics play a big part in things, but you need to work hard to stay in shape,” said Selter.

And to build a following.

Weinstein’s Instagram account, @mamaselter, has more than 200,000 followers. Even Grandma is getting in on the game with her account, @grandma_selter, with nearly 9,000 followers.

“Jen always tells me, don’t sit at home on your butt. Get up, walk. Whatever little bit you can do, just do it,” said Jacobs.

The septuagenarian stays fit with walks along the East River and no pasta.

“If I eat bread, I just eat the crust,” said Jacobs.

But all three women indulge in the occasional piece of dark chocolate or Levain cookie.

“A sweet tooth runs in the family,” said Selter.

LOIS JACOBS, GRANDMA AGE: 72 GO-TO WORKOUT: Bicycle or treadmill, 30 minutes a day. Light weights for arms. “Jen’s gentle when she works out with me. You have to take it slower when you get older,” said Jacobs. JEN SELTER, INSTAGRAM STAR AGE: 24 GO-TO...

JILL WEINSTEIN, MOM AGE: 50 GO-TO WORKOUT: Leg lifts and kick backs with an exercise band on her ankles. “It’s something I can do at home while I’m talking on the phone,” said Weinstein.