DNA PATERNITY....DIMPLES AND hereditary, strange situation but reality my friend has a son with dimples and i?

Anyhow I told her that dimples come only from the mother/father through the "Y" chromosome. She doesnt believe me (I could and very well be wrong I am no doctor but from what I have heard, which may have no validty) but this guy she used to fool around with has a dimple so it like makes me curious if its this other guys son. I just dont know how to say it her and be direct. Its like GO ESTABLISH DNA!!!!!! You know, what would you do? would you tell her take her son for a dna test with this other guy, would you just stay out of it, would it really hurt her feelings, like I care as friend but I am thinking how it will affect her son eventually if he wants to know his father its really all sort of screwy... what would you do?? We have been friends since the 2nd grade so its been 20 yrs of friendship I wont throw friendship away but he is my godchild