There are two different ways to describe a family tree. You can start with an individual and trace their ancestry through parents and grandparents and beyond to produce a picture of the variety of human beings it takes to make up any one of us. That’s genealogy. The other version is to pick someone from an earlier generation – king or commoner – and count their direct descendants. That’s heredity. But the choice between the two approaches – one spreading out backwards and one spreading out forwards – is only possible because earlier generations tended to have multiple offspring. Once that ceases to be true, family trees start to look the same from both directions. That has never happened before and it is hard to know what it will mean. But it is going to feel oppressive.
— Read on www.lrb.co.uk/the-paper/v47/n21/david-runciman/are-we-doomed