Well, plus, it kinda sounded like DrDeth was saying it was more defensible to delay testing when the victim had no idea who the perp was. But as you point out, it’s a shorter jump from proving sex to proving rape with a stranger in a dark alley, so if anything those are the kits that really need to be tested.
Before DNA, blood groups could be used to at least eliminate some suspects.
After some serious assault in a London housing estate, the police ‘persuaded’ all the males to provide a blood sample. Later on, a researcher let it slip that 20% of the boys were not the sons of their fathers.
Cite?
No cite since this was before the internet was a thing. It’s not far-fetched though:
Researchers pawed through a host of scientific articles published around the world from 1950 through last year. The perceived “paternal discrepancy rate,” as it is called, ranges from less than 1 percent to as high as 30 percent in the various studies. Most researchers believe the rate is less than 10 percent.
What I find far-fetched about the story about the London housing estate is that a researcher would let something like that slip, given how much of a mess that would cause.
It is if you know that more recent analyses, using the increasing wealth of DNA databases, have shifted the estimates for “paternal discrepancy rate” downwards from the oft cited 10%. And more damning for the story, blood group information can only rule out paternity in a small fraction of cases from father son data only(son is group O, father is AB), otherwise you need the mother, who presumably wouldn’t be in that data.
It’s a nonsense story based on prejudice against poor people.
Ignoring that the data wouldn’t let them make those conclusions, why would they even do that analysis. It’s not like it would drop out of the simple sorting of the men into two piles required to see who was a candidate to have left the biological evidence at the crime scene.
I always thought it was a story based on male fears of female infidelity.
Considering only 4% of UK are AB blood type, it would be difficult to identify 10% in error, let alone 20% based on blood type of father and son. Although I heard the same story decades ago (1990?) but based on a high school teacher giving his class an assignment on blood types. The math gets a bit more complex when you know both parents’ blood types, but still - that’s a little far-fetched.
Certainly DNA can be accurate, but we still don’t hear of a plethora of DNA issues where surprises come out. I suspect in the majority of cases, the alleged father is aware of the fact or the possibility that he may not in fact be the father.
There’s a lot that’s far fetched about that story - and a researcher letting something like that slip is the least of it. First you have the issue of identifying father-son pairs- why would the police compare a father’s result with his son’s? In fact why would the police even know that A is B’s father? Because they live in the same household? So what ? Even if you somehow found that A and B live in the same household and that A and B identify themselves as father and son while A couldn’t possibly be the biological father of B - you still don’t have any idea whether there is a “parental discrepancy” unless “parental discrepancy” includes cases where a man knows he is not the biological father such as adoption, a stepchild, a conception using donor sperm . The police certainly wouldn’t be asking about any of those things if they were looking to identify someone who committed assaults.