Robin Hanson describes the status quo as a conspiracy against cuckolds. Many of his students think that the husband is at fault if his wife goes outside the marriage.

Your discussion of surnames seemed a little unclear. The way it happened was actually favorable for quantitative conclusions on a name like Sykes. Before about 1150 nobody in England had proper surnames in the sense of modern usage. After about 1300 everyone had one. The names are either locative, occupational (e.g. Carpenter, Mason) or paternal (e.g. Robertson, Anderson).

One complication is that place names were used by the upper strata to mean ownership of land in the area, or of the local manor house. Some of these became surnames. This adds only a century or so of uncertainty in estimating chances of nonpaternity.

Another departure from the rule is that some Norman names persisted. The Corbett family produced a Sheriff of Shropshire county in the late 20th Cent., descended from a Roger Fitzcorbett who was 18 at the time of the Conquest and probably took part.

I don’t think these considerations apply to the Sykes family. There is a reasonable sample size and the distribution of the name is still highly circumscribed, so it’s good estimate of the rate of nonpaternity for a rural setting in England. It would be interesting to know if the higher rates are for urban populations.

The issue came up long before sequencing was possible. Human “blood groups” are (glyco)proteins on the surface of red cells that have a clear Mendelian inheritance pattern. There are about a dozen common blood groups and most of them were worked out by some industrious British blood bankers in the 1940′s and 50′s. The procedure was to collect blood from many members of a large family and check the known blood groups to establish paternity. Then they could eyeball a pedigree chart to find a Mendelian pattern.

In the course of these studies, non-paternity turned up in a small but noticeable fraction of the families, consistent with Sykes’ frequency estimate. They elected to quietly drop such a family from the series, without telling the subjects. It’s a reasonable decision, although one could think of examples where informing the subjects would be beneficial.

(My information is word-of-mouth from a blood banker who knew some British blood bankers from professional meetings and courses.)

As it is, my newborn was part of a pilot study to detect over 80 different genetic conditions – such as Fragile X and micro-deletions – in utero. This was because of my very rare Tay-Sachs mutation, we were flagged as being study eligible.

In Colorado, DNA evidence is not conclusive on the question of paternity. More than five years after a child is born, the presumption that a person married to the child’s mother is the father of the child is binding and conclusive, notwithstanding DNA evidence to the contrary.

Also, genetic parents have no special preference in parenting time and parental responsibility decisions within a “best interests of the child” analysis that can also include any people in “possession” of the child, and people who have spent substantial recent time with the child (e.g. step-parents or extended family).

Basically, our jurisprudence has very deliberately decided that fatherhood (and motherhood), in law anyway, is a psychological bond that often concides with but is not determined by genetic relatedness. A father is someone who has acted like a father, not necessarily just a sperm donor.

Similarly, in the area of assisted fertility, we look to the intent of those involved rather than genetic relatedness.

Generalizing concepts like parent on a non-genetic basis (and mostly a gender neutral basis) has made this area of the law rather more complicated than it was in the “good old days” but it has also provided considerable stability as technology and social norms evolve.

why would you say conservatives? (just so you know, i identify as conservative)