Is my suspicion warranted?

I just played a game with an opponent and afterwards, as I often do, I went to his/her profile to see if I could learn more about them. What I found in their games history was odd. I wonder if I should be suspicious of this member.

Here's the deal. In their games history it shows them playing another member with exactly the same name as theirs except that the user name ends in a "2" instead of a "1". The number 1 member says they were born in 1997 and the number 2 player says they were born in 1970. So they could be father and son/mother and daughter, but the birth date for number 2 is sort of suspicious too: January 1st 1970. 

Number 1 has a rating on Standard Live Chess of just under 1200 and number 2 has a rating on same of 1316. Oh, and when they play they play unrated games. So their ratings stay the same.

Anyway, I had never seen this before I just have been wondering about it. Any reason to be suspicious or not?

27 year difference; i.e. 1997 - 1970 = 27. Yes I was suspicious of boosting their rating, but of course playing unrated refutes that. But maybe concealing their rating? I don't know. I thought it was strange but I am relatively new here. Maybe this kind of thing is par for the course?

As long as it's two people playing against each other, I don't see a problem with it.

People playing each other from the same location (as would happen, e.g., with family members) are supposed to play unrated games only.

Nothing suspicious there...

Probably father-son/mother-daughter/mom-and-son/dad-daughter/everything except uncle and nephew.

@ivandh:  thanks.