“THE fathers have eaten a sour grape, and the children’s teeth are set on edge.” Steeltown Murders: Hunting a serial killer (BBC1, Tuesday of last week) presented a startling contemporary update of Jeremiah’s prophecy (31.29).

This gripping documentary followed the dogged hunt for the killer of three young women beaten, raped, and strangled near Port Talbot in 1973. The case sparked Wales’s biggest murder hunt — but, despite overwhelming police attention, no suspect could be identified. Interviews with family and friends still alive today told how deeply the whole community was affected (a truth usually overlooked in TV murder dramas).

There was not only the horror of bereavement and desolation suffered by parents and siblings, but the suspicion that blighted those who were thought possibly guilty; the sense that the killer was probably still living locally; and fear and suspicion destroying what had been a safe and happy place. Thirty years later, DNA technology reignited the case. After further stalemates, a radical solution was proposed: criminality frequently runs in families; so would the DNA of a known offender identify his father as the murderer?

A 50-per-cent match was found with a local car thief, but his father had died in 1990. Sensationally, permission was granted to exhume the body, and DNA from the corpse’s tooth was a perfect match with the stains found on one of the victim’s clothing. So, here a child proved, despite himself, his parent’s guilt, and finally brought some peace to all affected.

BBC1 has been showing a four-part true-crime series based on the case, which I had planned to compare with this “companion documentary”; but, as always, the unvarnished truth proved more compelling than any constructed drama.

Vicky McClure: My grandad’s war (ITV1, Monday of last week) showed a contrasting familial relationship. Ralph, aged 97, has only recently begun to talk about his part in the D-Day landings; his proud and loving granddaughter took him back to Normandy to revisit the scenes, learning along the way about the privations, losses, and trauma that the men had suffered. It was simple TV, but deeply affecting.

In Who Do You Think You Are? (BBC1, Thursday of last week), the actor Claire Foy learned for the first time about two ancestors who had a brush with death. Her paternal great-great-great grandfather John was swept up with other suspects after the 1867 Fenian “Manchester Outrage”. Despite anti-Irish hysteria, the court eventually believed alibis — but he might well have been hanged alongside the three convicted under the unsatisfactory charge of joint enterprise.

Foy’s maternal great-great-grandfather, a serving soldier, had drowned during a cross-country race. The people of Carlisle raised £500 to support his destitute widow and their five children.