Little details like this can really make a game stand out. While I did not find any developer comments on this, it does appear to be using Subsurface scattering, which is a mechanism of light transport in which light that penetrates the surface of a translucent object, is scattered by interacting with the material, and exits the surface at a different point [wiki]. The next slides talk about it!
Interestingly, Red Dead Redemption was praised online for this including this very effect!
https://www.reddit.com/r/reddeadredemption/comments/a6az2u/the_fact_that_light_makes_your_ears_glow_like/
Little details like this can really make a game stand out. While I did not find any developer comments on this, it does appear to be using Subsurface scattering, which is a mechanism of light transport in which light that penetrates the surface of a translucent object, is scattered by interacting with the material, and exits the surface at a different point [wiki]. The next slides talk about it!