Like father like son?

[Beestie]

Its an odd suspicion to have and there might be other reasons he is not consciously aware of for feeling this way in addition to the physical resemblance issue (things he may have heard or seen when he was young, for example).

Any word on what his mother or grandparents looked like? If any of the remaining five look anything like him, I'd calm down a little. If none do, I'd be googling for local DNA labs.

Tell your buddy to ask the lab if they can use a passive DNA sample (hair, fingernail clipping, etc.). Little tough to explain why he needs an inner cheek sample without giving up the real question.