I agree that the photograph has beauty in its humanity. I guess its best to use your instinct and judgment when taking the photo.
I too have a similar goal, only mine is quite silly, and I still want to do it for my scrapbook. I have a goal of taking celebrity look-alike photos. I still do it occasionally, but it is difficult to get the snap while the subject is unaware.
It all started for me when I was in Catalina, and on the boat we were on, was a man who looked exactly like the Dalai Lama, but he was wearing a hawaiian shirt, and I found that contrast hilarious. So I took the picture with the Dalai Lama guy behind my ex-husband, pretending to take a picture of just my then husband.
When in Ireland, my daughter and I saw a David Letterman look-alike, so I photographed him with his friend on the Ha’Penny Bridge, but pretended I was taking pictures of the surrounding sites.
Everywhere I go, I seem to see separated-at-birth look alikes,and it’s just a silly amusement of mine. Seems rather shallow after viewing your photo, however.