Grandma’s trauma – a critical appraisal of the evidence for transgenerational epigenetic inheritance in humans

Can molecular memories of our ancestors’ experiences affect our own behaviour and physiology? That idea has certainly grabbed hold of the public imagination, under the banner of the seemingly ubiquitous buzzword “epigenetics”. Transgenerational epigenetic inheritance is the idea that a person’s experiences can somehow mark their genomes in ways that are passed on to their children and grandchildren. Those marks on the genome are then thought to influence gene expression and affect the behaviour and physiology of people who inherit them. 
The way this notion is referred to – both in popular pieces and in the scientific literature – you’d be forgiven for thinking it is an established fact in humans, based on mountains of consistent, compelling evidence. In fact, the opposite is true – it is based on the flimsiest of evidence from a very small number of studies with very small sample sizes and serious methodological flaws. [Note that there is, by contrast, very good evidence for this kind…

Genetics, IQ, and ‘race’ – are genetic differences in intelligence between populations likely?

Last week (May 2nd 2018) the Guardian published a piece by me headlined “Why genetic IQ differences between ‘races’ are unlikely”. In it, I argued that the genetic architecture and evolutionary history of intelligence make it different from other traits and inherently unlikely to vary systematically for genetic reasons between large population groups.
Image credit: I was rather quickly (and, in some cases, rather aggressively) taken to task by a number of population geneticists on Twitter for being vague, overly general and hand-wavy, and for ignoring or not citing relevant papers in population genetics. Or indeed, for being flat out wrong. (See also a critique here). Some of those criticisms may well be valid, but some reflect the limitations of writing a short piece for the general public, so I wanted to go into more detail here on my reasoning.
The other criticism was that I seemed to be making statements as if they were str…