[first quote]

OK

Yes, that's theoretically sound i.e. this could stop last-round defection ever entering the population. Again it could be tested in vampire bats and other reciprocating species.

Well, we know that a fair number of historical human legal systems allowed the sins of the father to be visited on their children:

• In Japan, Samurai revenge killings could also kill the perpetrator's family.

• In the Bible/Torah, while humans are banned from killing a son for the sins of his father, it's also stated that God will punish the next four generators for the sins of one person. (It's also suggestive that they needed to ban killing the son for the sins of the father.)

• In Afghanistan, the cultural practice of using daughters as currency to settle disputes of their relatives is called baad; the girl is then typically abused. (I am assuming that, since they are being treated as property, they can be confiscated after death to settle debts just like any other property.)

• In Hinduism the Laws of Manu (4-173) state that "If (the punishment falls) not on (the offender) himself, (it falls) on his sons, if not on the sons, (at least) on his grandson."

• The Taoist Treatise on Response and Retribution states that "If at death an unexpiated offence be left, the evil luck will be transferred to children and grandchildren. Moreover, all those who wrongly seize others' property may have to compensate for it, with wives or children or other family members, the expiation to be proportionate up to a punishment by death."

(As an aside, thank you for your fantastically well-written and well-thought out comment.)