"God is just the people you love," I heard a doctor say this weekend. I was guessing she was Hindu, a religion that does not actively seek to expand or convert others and is still one of the world's largest mainly, I read, due to population growth. She was affable and unphased and even cracked anthrax jokes with chirpy paramedics while my sick friend was puking herself a shade off-beetroot. God bless the NHS.

And whether it's stains over the streets of Belfast, or cutting myself shaving, I have always wondered just how much there is in blood. Not in terms of molecular genetics, biophysics and Genome projects but in terms of family and extended family and race and faith.

There is no evidence that race exists. If one travels across this globe by land one will notice skin tones and physiologies vary by degree. If Charlotte Church bunked into a Wu Tang Clan photoshoot she'd be rumbled by even the most casual of fans but that does not imply the existence of two races, or three. However many one is supposed to accept exist. Race is socially more trouble than it's worth and scientifically bankrupt. Dependent on which criteria one uses any number of groupings may appear. Using lactose tolerance to group ourselves, for example, will result in north western Europeans, certain east African groups and Sari Indians falling into the same race, and everyone else into another.

Race is relativism and the continuing sense for race comes from a defensive/offensive reaction. Even embracing race as an immutable social concept seems determined to end in racism. We are one breed separated only by faiths (often mutated by diaspora, turned on the pivot-table of seeing oneself through the eyes of a dominant culture and restressing one's faith accordingly), sensibilities and a look. I once was surprised when Spike Lee said he didn't find "white girls" attractive, and still am when I meet, for example, girls who don't go for oriental guys. I shouldn't be. One has to conclude that this not an indication that human aesthetics betray any kind of deepset racism, but that our personal responses to physiognomies can sometimes be grouped at a broader level.

Metaforces and status, as far as I can see, are nowhere yet discovered in the blood. But the re-examining of any group who insists on their own exclusivity through any variant of lineage (blood, with all it's theatre really shouldn't be used as a catch-all for lineage) must be done with care. Invariably this tradition is tribal in origin. Land, property and title are passed from a father to his sons. Where no sons are had, the daughters of that family inherit but are forbidden to marry outside the tribe. Whether this is the roots of Jewish matrineal descendency is impossible to say.

Any sort of swinging, post-modern approach to faith may be fine until one wishes to join an exclusive group (I've met Turks in Berlin's Kreutzberg who are not recognised as German despite living there for generations) or are confronted by an aggressor who has a far more austere approach. Islam, a religion which has a history of military conquest leading to forced conversion to almost rival Christianity, has also gained followers in groups (in Indonesia, Africa and recently amongst Afro-Americans) who see it as resistance to oppression with roots in Judaeo Christianity.

It's a good thing that so much of the world now sees the lack of humanity on show in Taliban Afghanistan. And when you or I might be targets, despite our personal beliefs, I'd all for prevention. My personal belief is that I could maintain my independence, sit down fairly and squarely with a Taliban, ask to hear his side of the story, listen to it with no preconceptions and probably still despise him. But so often the end of a war is about negotiation, not resolution. Politics. And many lowly Afghans will get it, despite their own personal beliefs.

Faith, spiritual or societal, is not in the blood but interpolated, carved to our baseboard at childhood. When global panic stations are called, or something domestic goes deeply wrong, we find faith in a model of behavior guaranteed to place us somewhere recognisable. Sikhs turn to Sikhism, Zoroastrians to Zoroastrianism. To my shame I uncork something special, listen to Johnny Cash and write.

The first real blood I ever saw was in a book in a garden shed at the end of the 1970s. My friend Karl said he wanted to show me something but that I would first have to promise never to tell anyone. I agreed and he fished about in a box on a high shelf and produced some adult magazines. We flicked through these and he then asked if I would like to see something scary. He goes back into the box and hands me a book called "Ulster: The Facts." Produced for a Republican-sympathetic America, at the height of the IRA bombing campaigns, this book was counter-propoganda from a Unionist perspective. After a preface explaining Ulster's contribution to America in terms of the parents of various Presidents, there followed a glossy full-colour snuff magazine, centrefold atrocity shots, people opened out and cooked like meat, in their own brown black blood.