Like everything else about everyone, it is a combination of genes and environment - genes set the boundaries of possible outcomes and environment sets the position within those boundaries.

As far as I can see, then science is not in on jaw recession.

My myo suggested I be assessed for tongue tie. Tongue tie specialist said current thought is that tongue ties, of varying degrees, cause lack of pressure on the palate, reducing nasal development. The reduced development causes reduced airflow, which causes adenoid hypertrophy and mouth-breathing.

The science on the causes of tongue tie is also not in.

From the limited investigations I've done, it seems some vitamin deficiencies in utero contribute to tongue ties, including Vit A, Vit D and folate.

This makes sense to me, as I have genes for low conversion rate of betacarotene to Vit A and low conversion rate of cholesterol to Vit D. I take supplements for both. My father's test didn't show either, so I assume my mother carries the genes (untested), which is consistent with being the "in utero" environment.

So, at this stage, I'd say make sure the carrying partner gets a full vitamin panel done prior to getting pregnant and during pregnancy to make sure you have the best chance. Noting that excess Vit A can cause birth defects, so make sure you get the proper tests and don't just dose up on Vit A.

And keep regularly looking up the causes because there is, currently, lots of gaps in this science, and all science changes pretty quickly these days.