A closer match with son than his mother! How?

[hudsonh]

I have common matches with two individuals. I can see from their Family Trees that they are a mother and son. The son is suggested to be a 3rd to 5th cousin whereas his mother is suggested to be a fourth to remote cousin. Why would the son have a higher c.m. with me than his mother? They match each other on the same Chromosome, there's just more there for the son.

[Jim Barrett]

Maybe some of that match comes from his father.