[saiya-jin]

Well there is only 12 years age difference between actors, but Chalamet looks 15-17 all the time. Maybe creators wanted to emphasize strict gene selection happening behind curtains, and people in year 10,191 have better healthcare/skincare on position of queen.

Never met 40+ woman who looked as if she just finished university? Smooth skin, no moles or wrinkles, energetic. Genes + upkeep + generally healthy lifestyle + good sleep. And probably no kids.

Its not outrageous to have 15 year old son and looking very fine, plenty of world even in 2022 start having kids before/at 20. Look at all the photos of young moms from Ukraine escaping, often almost teenagers around young mom, in age that here where I live local women start thinking about having a child.

[HelloNurse]

Considering the peculiar genetic projects of the Bene Gesserit and other Dune groups is unnecessary: the real world trend of somewhat aged people looking so good that they can pass as significantly younger (in particular, actors who are credible as younger characters) can be easily and obviously extrapolated to the wealthy nobility of a far future high tech SF setting.

Jessica Atreides at about 40 is supposed to look so extraordinarily youthful that a younger actress like Rebecca Ferguson is needed.