The USA is a funny old place at times, a land of contradictions, as the tourist ads might have it. Take homosexuality as an example. You'll be pushed to find a country that hosts more lavish and celebratory Gay Pride marches, but when it comes to gay characters in mainstream movies, well that's a different kettle of fish. Gay characters can be funny, they can wrestle with confusing feelings or the process of coming out, but complete, unflinching, unprejudiced acceptance is rare indeed. I'm not saying that things are even close to perfect in European cinema, but without the Hollywood obsession with a restrictively narrow demographic there is a lot more room for manoeuvre. And I can't help taking an instant liking to any film in which a mother accepts that her son is gay with the sort of cheer usually reserved for news of an impending marriage.

The mother in question is the jovial Béatrix (the delightful Valeria Bruni Tedeschi, who may be familiar to UK viewers for her role as the charming PR woman in Tickets) and she and her husband Marc are taking their summer vacation with their two teenage children, Charly and Laura, in the seaside house of Marc's youth. They are soon joined by Charly's friend Martin, and the two boys spend all of their time together and are clearly very close, closer than just good friends, Béatrix reasons. She's not shocked, surprised or disappointed, but delighted at the wonders of young love, but in this particular household, nothing is quite as it seems. Charly and Martin are close, Martin is certainly gay, but what of Charly? Mind you, Béatrix, although seemingly content in her marriage, is also having a steamy affair with Mathieu, who decides he would also like to spend his vacation by the sea, resulting in late night phone calls and grabbed afternoons of sex. Marc suspects nothing, but then he seems to be developing an unexpected fascination for the young Martin.

All of which has the makings of a madcap sex farce, but the striking thing about Cockles and Muscles [Crustacés et coquillages] is its easy-going and unforced approach to its characters and its complete lack of hang-ups about their sexual preferences and activities. Marc and Béatrix are good together (whether eating oysters or performing a song for Charly and Martin, they appear to be as close as a couple could be) and Béatrix's affair with Mathieu is clearly doing her as much good as the summer sunshine. If some friction does develop between Charly and Martin when the latter goes cruising for sex at a traditional local pick-up spot, then it's more about how it affects their friendship than anything approching a lovers' tiff.

Internal conflicts inevitably develop and do sometimes have a slightly sex farce aspect to them. The bathroom shower in particular becomes an amusing location for the relief of sexual tension, a place for Charly and the frustrated Martin to secretly whack off, for Béatrix and Mathieu to frolic while the others are occupied elsewhere, and for an irritable Marc to get all flustered when he catches sight of Martin doing what young boys will do. Increasingly, just the sound of the shower running becomes an emotional trigger, prompting Martin to become all hot under the, well, you know what, and Marc to either sneak out of the bedroom to take a peek or complain about the drain on the hot water supply.

The revelations really get under way with the introduction of good-looking plumber Didier (a divinely cast Jean-Marc Barr), who comes on aggressively to Charly when all he was doing at the local hook-up point was tailing Martin, and only backs off when he finds out just who Charly's father is. Later, he is called to the house to fix the hot water, which Marc has sabotaged, and... well, go see for yourself.

It all unfolds in amiable and good-natured fashion, right up to the almost fairy-tale ending and song-and-dance finale. There's nothing particularly groundbreaking here, but the performances are most engaging, the characters increasingly likeable and involving, and the cheerful acceptance and later celebration of the positive effects of giving in to your desires, whoever they may be for, certainly put a big smile on my face.

Before I commit myself on either picture and sound, I should mention that the preview discs we have received for Peccadillo releases have not so far been fully representative of the finished product. Anahi Berneri's involving A Year Without Love in particular had a transfer that I could not believe even a small independent company would put out on DVD (as it turned out it wasn't, and the final release disc apparently looks fine), and as a result we did not review it. Like that disc, Cockles and Muscles lacks the menus that presumably grace the final release, but the print on offer is an anamorphic widescreen one and in pretty good shape, and I'm going to take a chance and presume that this is the one that appears on the final release disc. There is a slight softness to the picture and the colour sometimes has a faintly 'aged' quality to it (which could, of course, be deliberate), but the contrast and detail is generally good. The film was shot entirely on High Definition Video, and the transfer appears to have been taken from the film print, not the hi-def master. The English subtitles here are fixed – I can't vouch for the release disc.

The Dolby 2.0 stereo soundtrack is very clear and has a good dynamic range, especially evident in the score. What I cannot be sure of is whether this is the only soundtrack available, as the method used to write the preview disc (a Sony hard disc/DVD recorder if I'm not mistaken) does not allow for multiple soundtracks. A couple of online DVD stores suggest the presence of a directors' commentary, but there's certainly not one of the preview disc.

Karaoke (5:29) features the two musical numbers in the film, complete with subtitles that change colour to indicate where you should be if you are singing along.

Listed rather wonderfully on the preview DVD sleeve as A Short Documentary: How to Shoot Wanking in the Shower (7:49), this is a fun behind-the-scenes featurette about filming, well, you can probably guess. It's preceded by a warning about the content, mainly for the sizeable prosthetic penis made and worn for the scene – an amusing moment has a female make-up artist surprised and embarrassed to be caught on camera while working on it, so to speak.

Outtakes (3:13) is a small collection of unused moments, a couple of which – Valeria Bruni Tedeschi falling off her bicycle being the most memorable – are certainly worth a look.

The Making of the Dance (Vaudeville) Sequence (15:19) shows the rehearsal and shooting of the final musical number and is narrated by co-director Jacques Martineau. Reference here is made to a deleted scenes section on the DVD, which is not present.

The Q&A With Olivier Ducastel & Jacques Martineau (63:36) is a two-parter, the first and longest recorded at the Cardiff screen festival and chaired by Sarah Howells, the second at the London Lesbian & Gay Film Festival in 2005 and hosted by Brian Robinson. The acoustics of the locations are less than ideal, but both are very interesting for anyone who enjoyed the film itself, with the shorter second Q&A being the livelier and funnier. There's a touching moment when the two directors, a gay couple themselves, are presented with a gift to mark their tenth anniversary together.

A film that would be too easy (and inaccurate) to pigeonhole as queer cinema, Cockles and Muscles definitely has a potential for wider appeal and deserves to find an audience outside of the club circuit. It's a thoroughly good-natured piece with a positive message for us all about relationships and desire, and is worth seeing for its cast alone. Peccadillo's DVD features a largely decent transfer and some very worthwhile extra features, and as such represents a good value buy for all but the more prudish, who frankly could do with spending a few days up at the fort.