I remember being told about an old science fiction television series about an alien invasion. In the series the only way to identify an alien from a human was that two of their fingers would appear to be fused together. I have never been able to identify what series this is from. I'm pretty sure I heard about this sometime within a few years of 1990. I had the impression at the time that this show was probably on sometime during the 70's or early 80's, but I'm not at all sure. Has anyone ever heard of this story?
It could be The Invaders TV show from the late sixties. The aliens could often be detected by a weirdly angled finger which sounds like what you might be thinking of with the fused fingers. As described on Wikipedia:
"Most of the aliens, in particular the lowest-ranking members or workers in green jumpsuits, were emotionless and had deformed little fingers which could not move and were bent at an unnatural angle, although there were "deluxe models" who could manipulate this finger."
It was re shown on BBC 2 in the UK in 90s which may explain why you heard about it then.