You would run the analysis and get absolute nonsense results, and then you'd swap a father for an uncle, or a mother for her daughter, and the alleles would all just suddenly line up.
We would never tell the families, and since the pedigrees were anonymized before being published there was no need to. Some secrets are just best kept buried.
IMO a paternity test should just be mandated to be done immediately at birth (or earlier even?). It avoids the tinge of distrust of "oh wow, how could you even think that of me?!" from the mother, whilst giving certainty to the man.
The period immediately after birth is one of the most dangerous times for children, and we (should) specifically take action to protect them in a moment where they are at risk and have no agency. A paternity test would increase the risk of harm to the child (either through violence, deprivation, or neglect). We didn't even get to the subject of possible violence against the mother either, which is likely.
Also, there's a second order effect you're ignoring: a mandated paternity test would change expectant mothers' behavior leading up to the birth. You wouldn't try to dupe someone if you knew you'd be found out. Or, if you weren't sure, you'd more likely be transparent.
The source of risk isn't performing the test, the source of risk is the father getting upset and killing the mother and/or child.
It might actually be that mandatory paternity tests reduces the background rate of familicide. All of the reports that I could find were only after the father had invested considerable time into raising the child as their own. The stakes of the deception are much higher. But if they know the day the baby is born (or earlier), then it's much easier to walk away. It also makes it pointless for the deception to happen in the first place.
I wonder how would you react if you received a notification that half your paycheck will be henceforth withheld to support some random kid.
this comparison is not entirely fair, because in this scenario, the kid's mother did not deliver a grievous, unforgivable insult to you - which is the case with those poor souls who got scammed into paying child support for some whore's bastard whelp.
the state doesn't give a flying fuck about the child's 'financial distress'. the state simply doesn't want to support it.
As others have stated above, this isn't really about protecting "family harmony" / "saving the child", it’s about cost.
If paternity tests were easily accessible, many men would easily contest child support and if successful, they would opt out. The state benefits from keeping paternity disputes out of court because it ensures that private individuals, rather than government welfare programs, remain responsible for child support.
If too many men successfully challenged paternity, the state would be forced to provide financial aid for more children, increasing costs. Restricting paternity tests shifts the burden away from taxpayers and onto unwitting fathers, all while claiming it’s about social stability.
1. Isn’t there a very high chance any particular male’s result is true for both father and uncle?
2. For young teen mothers, sometimes a family of older mother and two assumed siblings is really grandmother, mother, child. Paternity and slightly maternity are secretly, generationally obscured. So two assumed female siblings might share less than half-sibling measures of autosomal DNA.
For 1 it depends on the penetrance model (a score on whether all individuals with the disease allele(s) express the disease phenotype: 1=all, 0.5=some, etc.) along with whether the allele's mode of inheritance is recessive/dominant, X-linked or not, and how consanguineous/inbred the pedigree is.
If I remember it right, if a father/son combo always express the disease allele, then the pedigree is x-linked recessive. If you see an uncle/son combo, and test for it, and the linkage score for the region of interest (the likelihood that the disease travels with the ROI computed over all individuals) goes up, then it's pretty suspect.
For 2, you could see the distribution of alleles without much computation. Siblings are expected to share X%, relatives Y%, unrelated Z%. By fitting to these bands, you could already see if the distribution of alleles was suspect. We never tested for mtDNA though, I don't think there were many chipsets for it back then.
1. Circumstances where both mtDNA and Y chromosome are shared between biological father and pedigreed father. I think the Biblical term is Levirate marriage.
2. Circumstances without Y where maternity is secretly disputable and paternity uncontentious. I think the researcher called this secret adoption.
At distances longer than several generations, is there noise in the measure of autosomal matches such that you cannot detect these?
1% of the human genome (3billion bp) is still 30M bases, which could easily contain 1 or 2 genes which you may have genotyped, depending on the resolution of your genotyping chip (usually 10M markers spread out over the entire genome, and usually clustered around variants/genes of interest).
So yeah, even 5 generations down these differences could be detected at the variant level. Even at 10, you could still _theoretically_ find differences.
I stress theoretically, because the chance of you having all the individuals from a pedigree genotyped at the same time using the same tech (and thus the same subset of common genotypes to compare) is slim to none.
I'd say 5 generations is a rough rule of thumb where the signal is not that much higher than the noise.
Clearly lots of people never listen in biology class.
E.G: both biological parents cannot be A and the kids be AB