Not an anthropologist - but instead of "How farming promotes inequality", I'd frame it as "How resource-producing capital promotes inequality". It could be livestock in a migratory herding society, or boats and nets when those were critical for fishing, or whatever.

> In contemporary Western societies, unigeniture is either considered wrong or is illegal; we no longer differentiate between legitimate and illegitimate offspring...

At best, those are common ideals in Western society. Try talking to an old attorney who does family law.