“When you think about how we arbitrarily divide up the entire world into girls’ stuff and boys’ stuff, none of those things make any sense,” said Courtney Hartman, the founder of Free to Be Kids and Jessy & Jack, two clothing brands aimed at offering more options for children. “There’s no reason boys should like dogs but not cats.”

As a mother of a boy and a girl, Hartman says the gender divide came into sharp relief for her when she was looking for matching pajamas for her kids. Both featured penguins, but one was marketed for girls and the other for boys.

“The boys’ penguins were fatter and wearing sunglasses,” she told me, “and the girls’ penguins were skinnier with eyelashes, rosy cheeks, and lips. I was like, ‘Man, those are penguins! This is messed up!’”

Until recently, finding alternatives to gender cliches in kids’ wardrobes was surprisingly difficult. But in the past decade, several small companies—mostly led by mothers, like Hartman, fed up with gender-assigned constraints—have cropped up to challenge cultural norms. Another entrepreneur in this space is Rebecca Melsky, who became frustrated when she couldn’t find any outfits featuring some of her then-2-year-old daughter’s favorite things—like trains, for instance—on clothing marketed for girls, at a time when her daughter only wanted to wear dresses.

The experience made her realize that she didn’t want to steer her daughter away from the dresses she loved, but she did want those dresses to incorporate designs that better reflected the full spectrum of her little girl’s interests.

“Before my daughter was born, my husband and I were like, ‘We are not going to buy her anything pink,’” said Melsky, the co-founder and chief operating officer of Princess Awesome, which makes dresses printed with trains, dinosaurs, the pi symbol, pirates, and other designs typically not found on clothing marketed to little girls. “As I was thinking about starting this company, I thought a lot about that. Why did I feel that way? And, later, why did I think that when she expresses a preference for pink and purple that it’s somehow lesser?”

Liking technology and liking the color pink aren’t mutually exclusive. (As a former little girl who likes both, I know this to be true.) Or, as Princess Awesome puts it on its website: “Because girls are awesome and girls get to decide what it means to be girly.”

“My [co-founder and business] partner Eva, her mother-in-law has this great saying,” Melsky told me. “You can’t tell children they have a choice, and then tell them they’ve made the wrong one.”

That’s also the message behind BuddingSTEM, a brand that makes science- and technology-themed clothing like leggings and dresses dotted with tiny rockets or apotasauruses. “You can be a girl however you want to be,” said Malorie Catchpole, one BuddingSTEM’s cofounders. “Wanting to wear tutus does not mean you can’t grow up and be a rocket scientist.”