I don't know about this study. You can stay out of the sun and not get wrinkly and "appear" younger in your 30s. You can be in the sun often, get tanned and wrinkly and "appear" older in your 30s.
I know when I look at my college's quarterly magazine for alumni, I like to read the alumni notes, people getting married, having kids, getting a job, whatever else news. Sometimes, the person includes a recent picture. Some of them are like "Wow, you graduated after me, but you look like 10 years older than me. Yikes."
There was this co-worker who recently had his 40th birthday. Nice guy and all. But, he looks like he's in his 50s.