The idea of keeping it in the family isn't a new one for the fashion world, with several collaborations happening between siblings. Donatella and Gianni Versace. Australians Camilla & Marc.

Er, Mary-Kate and Ashley Olsen. Sam and Jeremy Galvin. You could be forgiven for not yet having heard of that last pair.

The Galvin brothers launched Descendant Denim earlier this year, a local label that incorporates denim, quirky printed tees and a small selection of merino, with a focus on organic fabrics, a commitment to being proudly made in New Zealand, and an old fashioned sense of craft.

"[The decision to start the label] almost wasn't totally conscious, it was something that had been subtly brewing. It was almost an instinctual decision more than an intellectual one," says Sam, who acts as the creative brains behind the label. "It was pretty close to a moment of temporary insanity."

Sam and older brother Jeremy launched Descendant earlier this year out of a small house in Glen Eden, after a lifelong passion for all things fashion.

"When we were in Europe, a lot of people would go to art galleries and things like that, but we'd hunt out cool boutiques," explains Jeremy, who has worked in the film industry for the last few years and recently returned from a surfing trip in Sri Lanka.

"We couldn't afford anything, but we'd just go in and look; we loved doing that, finding stuff that was kind of outside, a bit edgier and a bit cooler."

That same outsider ethos informs their label, which has found a home in key high-end boutiques around the country including Auckland's Made, Jaimie Boutique and Wunderkammer, which stocked the label from its first season after never having sold denim before.

Plume has also taken them on, which Jeremy says was, "amazing kudos for us".

"They took on our whole collection, that was a moment of celebration; someone who is so iconic in the fashion industry, Margi of NOM.d coming to look at your range... They got what we were doing straight away. We showed people some prints, and they'd go 'Oooh that's a bit scary', but we showed the girls at Plume and they'd go, 'aw, cute."

"I think people have realised that it's authentic, it's genuine; we're not looking for any glitz and glam," says Sam.

Denim is a major market within the fashion industry, as is the organic, environmentally friendly niche; so combining the two seems to be a very smart business idea.

The pieces are all made in New Zealand from internationally certified organic denim, with distinctive cuts, hand finishes and small details like organic leather patches for guys and girls. It's a focus on using the best fabric that they can get their hands on that makes the label stand out.

"Being organic was always, in my mind, one of the key bases for the label. Organic fabric tends to be top of the line because it is a premium product, and the other thing is that it is sustainable," says Sam.

"Because of what we're producing, there's no reason why we can't use organic, sustainable fabrics, so given the choice, why wouldn't you? It's low impact, it's better fabric, generally, it makes sense on every level.

Everything is also fair trade certified, that's another key thing, nothing is made in dubious circumstances."

Their commitment to continue being made in New Zealand is something else that makes the label relatively unique, in a time where a lot of production is being moved to China.

"People are sceptical, even the guy who launders our jeans and does our washes, he says that as soon as people get big enough they take it elsewhere - but we really are committed to staying here regardless. If we have to train our own machinists to keep up with demand then we will," says Sam, who has an art background.

This has helped inform the distinctive T-shirt prints which sit alongside the denim and merino.

"They're best described as mixed media. Obviously I draw on my art background a lot, but it's not exclusively drawings, sometimes it's photos, sometimes I'll take photos myself and then drawings, it's all then worked digitally through Photoshop.

"For every print that I'm happy with, there's probably one or two that goes by the wayside. It replicates the art thing for me, you paint for three hours and you only get an hour of good painting, it's the same kind of thing."

Each season has a loose theme or idea, with next season's winter range (only their third) looking at "strange objects", featuring fantastically bold and sometimes freaky prints including lace-printed skulls and bows, surreal faces and more.

"There's always a feeling over the whole collection, sometimes it's hard to find, even for me. It's hard to articulate, but it's a sense of something.

This season it's sort of a skewed dandy-ism, heralding back to Edwardian or Victorian but in a contemporary kind of way, strange objects, that sort of thing."

The collections are also slowly expanding to include fashion pieces, with merino appearing for winter.

But it's a long-held passion for finding the perfect pair of jeans that's helped push the pair to develop their design processes.

"The more you know, the more you realise you don't know. To be honest, when I started I didn't realise denim was so hard to get right."