Our smoking habits and our sex lives are about what we do. Being Black or White or any combination is not. It's out of our control.

And the same may be true when it comes to whether we get hooked on smoking, that it's built into us. And that may well be true of our sexual orientation as well.

For an adoption agency to make a principled decision against putting children into a smoking household does indeed involve discriminating against people who smoke.

But I think would be wrong to close down an adoption agency for discriminating in this matter, just as I think it would also be wrong to close down another agency which decided that it would be wrong, on balance, to exclude smoking households from their books.

There are some 150 adoption agencies or so operating in the UK. It is not necessarily unreasonable that on some issues of lifestyle there might be some difference in the range of people with whom they work.