I have seen some dumb movies in which a kid grows up and looks exactly like his father . I know some twins do that but is there any chance of this happening between a father and his son or somethin ? Even though it has probably never happened (or has it ?) is there a chance it could happen theoraticaly ?
As I understand it, the number of DNA combinations is theoretically finite, so yes. Also, your question is limited to phenotype, which wouldn’t require two people’s DNA to be perfectly identical to produce the same physical appearance.
I’m sure someone who knew the genetics involved and was well versed in combinatorics could give you some reasonable bounds on the probability, but the genes that contribute to phenotype aren’t well defined yet. Suffice to say, the probability is very low. Like “number of atoms in the universe” low.
And this is all assuming every strand of DNA in your body is identical to each other, and is YOURS. But mutations happen all the time, and there are cases of finding traces of DNA corresponding to a person’s mother, child, or older siblings in their body, just because they were exchanging blood during pregnancy and those cells can hang around. And you never really know how those cells will propagate or how they’ll affect the person’s development. So in reality it may be much more difficult to compute than in theory.