Set two genetic twins side by side with only one routine difference — sunscreen — and the simulation illustrates a real number: UV exposure accounts for roughly 80 to 90% of visible facial aging.

noli's read

That number isn't a marketing invention: a landmark study (Flament et al., ~300 Caucasian women, Clinical, Cosmetic and Investigational Dermatology, 2013) measured an average "sun damage percentage" of 80.3% in visible facial aging, and the US EPA commonly cites up to 90%. That research compares sun-exposure profiles ("sun-seeking" vs. "sun-phobic"), not actual twins, so the "same genes, same routine" framing is a teaching simplification — but the point it illustrates is solid and already well documented in the corpus (an Australian RCT found about 24% less photoaging with daily vs. discretionary sunscreen use over 4.5 years). The post's simple takeaway — daily rather than occasional SPF — remains the single best-proven skincare habit there is: nothing new here, but nothing to correct either.

the sources

1. 1Green AC, Williams GM, Logan V, Strutton GM 2011
2. 2Hughes MCB, Williams GM, Baker P, Green AC 2013