I agree! He looks quite like J, and quite like the son my sim has with J in one of my save files. In that game the daughter she has with J looks quite like him too, maybe even moreso than her brother. Her cheekbones in specific stand out as being J's, but that's a good thing (I like J's cheekbones). She's actually very pretty, I was just noticing today how pretty she is. And the boy is nice-looking too, of course.
Another family that I've found that seems to have very strong genetics is the Goth family, at least the males of the Goth family. In one of my saves my family's oldest daughter married Alexander (well, once he had some tweaks to his ears, chin, and nose length, but that's all I changed, I promise, lol), and they had two sons and a daughter, and in another save my sim has three sons with Mortimer, and there's not a one of those six children you wouldn't peg as being a Goth.