I agree, I think looking younger is in the genes... though I'm not completely convinced some risk factors for CFS/ME aren't in our genes as well.
My mother was able to pass herself off as a almost 20 years younger than she was for the majority of her older adult life. Myself? I'll be 49 in a few weeks and am regularly mistaken for being in my 30's... but almost feel insulted lately (even if I know it's meant to be a compliment) - as my sister who is 61 routinely gets told how great it is that she has such a great older sister in me.
As for 'sun' exposure, my mother didn't get chronically ill until her mid-60's and would get so much sun routinely that her grandchildren couldn't make sense as to how grandma could be a black woman (she wasn't - just VERY tanned, although definitely some american indian heritage)... and all her children be white. My eldest two brothers aged at a normal rate, though they have their fair share of health issues... I've not seen them talk about it as if it was 'chronic illness'. My sister has had health issues her whole life (but she also does a great job of engaging in self-destructive behavior - so no idea if she is truly ill or the years of eating junk food and not managing her weight, and smoking and drinking to excess are key components). My youngest brother who is in his late 30's though? He also looks a LOT younger, my older brothers were all graying by then... and lo and behold? He has been diagnosed wtih llyme disease...
Out of the six of us (my mom and her 5 children), four of us have had chronic illness related issues and those same four were the ones that look consistently 10-20 (maybe more) years younger than we are... vs. the two that didn't get sick turning gray and actually looking 'aged' in their mid-30's.
so... definitely not something scientific... and impossible to take this information as anything more than an interesting coincidence....
but I wonder if the risk factors for the chronic nature of illness are linked genetically to the genetic traits that also slow the aging?
I definitely think that if this had a genetic 'cause' that we would have been able to find it by now... and a LOT of people get ill after a virus or traumatic event which can cause stress, there are still others that got ill gradually - a genetic risk factor that can be compounded by stressful body events (like the virus, or a traumatic event, or just a stressful life altogether) might be something that could have something to do with all this. That said, I don't think it's as simple as finding a single genome or snp... I think there are so many layers of details and nuances around genetics that are still unknown to most of us... and I imagine if it is ever found it will be a complex web of linked genes that work on certain processes that when there are too many failures in the system - is when the system gets over whelmed and cannot function any longer. Methylation might be a part of it, but it could be a tiny piece of the puzzle... I do wish that research could catch up with some of these things and find some helpful answers... but there is so much we may never learn in our lifetimes.