(a) The treatment introduced 'green' cells which functioned as an extreme form of gene therapy, overwhelming and replacing the patient's immune system AND DNA (modifying muscle and nerve tissues, etc., in the subject, but also making inheritable changes). Hence the children of two subjects (even assuming the new traits are recessive) would PROBABLY inherit AND express the changes.An interesting story. I must say, I'm surprised that the surgical change is at all expected to become a genetic change (that is, I believe, related to Lamarckian evolution); and I'm even more surprised that Mike would want to take orders from the army after rejecting his parents so thoroughly.
(b) One of the changes was increased aggression. Mike would find the Army, which not only accepted but encourage aggression, very appealing...
RM